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{{Short description|Decentralized digital currency}}
{{Redirect-distinguish2|₿|"฿" for [[Thai baht]]}}
{{for|the colloquial expression for coinage|Bit (money)}}
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{{Redirect-distinguish-text|₿|"฿" for [[Thai baht]]}}
{{Use dmy dates|date=June 2018}}
{{pp-extended|small=yes}}
{{Use dmy dates|date=March 2024}}
{{Use American English|date=December 2017}}
{{Use American English|date=December 2017}}
{{infobox cryptocurrency
{{infobox cryptocurrency
| currency_name = Bitcoin
| currency_name = Bitcoin
| image_1 = Bitcoin logo.svg
| image_1 = Bitcoin.svg
| image_2 =
| image_title_1 = Prevailing bitcoin logo
| image_width_1 = 150
| alt1 = Prevailing bitcoin logo
| image_width_2 = 110
| subunit_ratio_1 = {{frac|1000}}
| image_title_1 = Logo
| subunit_name_1 = millibitcoin
| alt1 = Prevailing bitcoin logo
| subunit_ratio_2 = {{frac|100000000}}
| precision = 10<sup>−8</sup>
| subunit_name_2 = satoshi<ref name="satoshi unit">{{cite web |title = Cracking the Bitcoin: Digging Into a $131M USD Virtual Currency |url = http://www.dailytech.com/Cracking+the+Bitcoin+Digging+Into+a+131M+USD+Virtual+Currency/article21878.htm |author = Jason Mick |publisher = Daily Tech |date = 12 June 2011 |accessdate = 30 September 2012 |deadurl = yes |archiveurl = https://archive.is/20130120051306/http://www.dailytech.com/Cracking+the+Bitcoin+Digging+Into+a+131M+USD+Virtual+Currency/article21878.htm |archivedate = 20 January 2013 |df = dmy-all }}</ref>
| subunit_ratio_1 = {{frac|1000}}
| plural = bitcoins
| subunit_name_1 = Millibitcoin
| symbol = ₿{{efn|group=infobox|The symbol was encoded in [[Unicode]] version 10.0 at position {{unichar|20BF|BITCOIN SIGN}} in the [[Currency Symbols (Unicode block)|Currency Symbols block]] in June 2017.<ref name="unicode-10">{{cite web |url = https://www.unicode.org/versions/Unicode10.0.0/ |title = Unicode 10.0.0 |publisher = Unicode Consortium |date = 20 June 2017 |accessdate = 20 June 2017 |deadurl = no |archiveurl = https://web.archive.org/web/20170620130342/http://www.unicode.org/versions/Unicode10.0.0/ |archivedate = 20 June 2017 |df = dmy-all }}</ref>}}
| subunit_ratio_2 = {{frac|{{val|1000000}}}}
| ticker_symbol = BTC, XBT{{efn|group=infobox|Compatible with ISO 4217.}}
| subunit_name_2 = Microbitcoin
| coin_definition = [[Unspent outputs of transactions]] (in multiples of a satoshi)<ref name="Antonopoulos2014">{{cite book |author = Andreas M. Antonopoulos |date = April 2014 |isbn = 978-1-4493-7404-4 |publisher = O'Reilly Media |title = Mastering Bitcoin: Unlocking Digital Crypto-Currencies }}</ref>{{rp|ch. 5}}
| subunit_ratio_3 = {{frac|{{val|100000000}}}}
| implementations = [[Bitcoin Core]]
| subunit_name_3 = {{lang|ja-Latn|Satoshi|italic=no}}{{efn|name=satoshi}}<ref name="satoshi unit">{{Cite journal |last=Bradbury |first=Danny |date=November 2013 |title=The problem with Bitcoin |url=https://linkinghub.elsevier.com/retrieve/pii/S1361372313701015 |journal=Computer Fraud & Security |language=en |volume=2013 |issue=11 |pages=5–8 |doi=10.1016/S1361-3723(13)70101-5 |access-date=25 November 2023 |archive-date=18 January 2023 |archive-url=https://web.archive.org/web/20230118052355/https://linkinghub.elsevier.com/retrieve/pii/S1361372313701015 |url-status=live }}</ref>
| plural = Bitcoins
| symbol = '''₿'''<br/>(Unicode: {{unichar|20BF|BITCOIN SIGN|html=}})<ref name="unicode-10">{{cite web |date=20 June 2017 |title=Unicode 10.0.0 |url=https://www.unicode.org/versions/Unicode10.0.0/ |url-status=live |archive-url=https://web.archive.org/web/20170620130342/http://www.unicode.org/versions/Unicode10.0.0/ |archive-date=20 June 2017 |access-date=20 June 2017 |publisher=Unicode Consortium}}</ref>
| code = BTC
| implementations = [[Bitcoin Core]]
| initial_release_version = 0.1.0
| initial_release_version = 0.1.0
| initial_release_date = {{Start date and age|df=yes|2009|1|9|p=y}}
| initial_release_date = {{Start date and age|df=yes|2009|1|9|p=y}}
| code_repository = {{URL|https://github.com/bitcoin/bitcoin}}
| latest_release_version = 0.16.1
| status = Active
| latest_release_date = {{Start date and age|df=yes|2018|06|15|p=y}}
| latest_release_version = 27.1
| author = [[Satoshi Nakamoto]]
| latest_release_date = {{Start date and age|df=yes|2024|06|17|p=y}}<ref>{{cite web |title=Bitcoin Core Releases |url=https://github.com/bitcoin/bitcoin/releases |via=[[GitHub]] |access-date=17 June 2024 |archive-date=17 June 2024 |archive-url=https://web.archive.org/web/20240617165811/https://github.com/bitcoin/bitcoin/releases |url-status=live }}</ref>
| white_paper = [https://bitcoin.org/bitcoin.pdf "Bitcoin: A Peer-to-Peer Electronic Cash System"]<ref name="paper" />
| forked_from =
| website = {{URL|bitcoin.org}}
| programming_languages = C++
| block_explorer = {{URL|blockchain.info}}
| operating_system =
| ledger_start = {{Start date and age|df=yes|2009|1|3|p=y}}
| author = [[Satoshi Nakamoto]]
| hash_function = [[SHA-256]]
| developer =
| circulating_supply = ₿16,858,762 ({{as of|2018|2|11|lc=y}})
| white_paper = [https://bitcoin.org/bitcoin.pdf "Bitcoin: A Peer-to-Peer Electronic Cash System"]
| supply_limit = ₿21,000,000 <ref>{{Cite web|url=https://github.com/bitcoin/bitcoin/blob/08a7316c144f9f2516db8fa62400893f4358c5ae/src/amount.h|title=Bitcoin source code - amount constraints|last=Satoshi et al.|first=|date=1 April 2016|website=|archive-url=|archive-date=|dead-url=|access-date=}}</ref>
| source_model = [[Free and open-source software]]
| timestamping = [[Proof-of-work system|Proof-of-work]] (partial hash inversion)
| license = [[MIT License]]
| issuance = Decentralized (block reward)<ref name="JSC">{{cite web |url = https://www.fincen.gov/sites/default/files/2016-08/20131118.pdf |title = Statement of Jennifer Shasky Calvery, Director Financial Crimes Enforcement Network United States Department of the Treasury Before the United States Senate Committee on Banking, Housing, and Urban Affairs Subcommittee on National Security and International Trade and Finance Subcommittee on Economic Policy |publisher = Financial Crimes Enforcement Network |work = fincen.gov |date = 19 November 2013 |accessdate = 1 June 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20161009183700/https://www.fincen.gov/sites/default/files/2016-08/20131118.pdf |archivedate = 9 October 2016 |df = dmy-all }}</ref><ref name="tcdecentralized">{{cite news |last1 = Empson |first1 = Rip |title = Bitcoin: How an Unregulated, Decentralized Virtual Currency Just Became a Billion Dollar Market |url = https://techcrunch.com/2013/03/28/bitcoin-how-an-unregulated-decentralized-virtual-currency-just-became-a-billion-dollar-market/ |accessdate = 8 October 2016 |work = TechCrunch |publisher = AOL inc. |date = 28 March 2013 |deadurl = no |archiveurl = https://web.archive.org/web/20161009205955/https://techcrunch.com/2013/03/28/bitcoin-how-an-unregulated-decentralized-virtual-currency-just-became-a-billion-dollar-market/ |archivedate = 9 October 2016 |df = dmy-all }}</ref>
| ledger_start = {{Start date and age|df=yes|2009|1|3|p=y}}
| block_time = 10 minutes
| hash_function = [[SHA-256]] (two rounds)
| block_reward = ₿12.5{{efn|group=infobox|July 2016 to approximately June 2020, halved approximately every four years}}
| circulating_supply = ₿19,591,231 ({{as of|2024|01|06|lc=y}})
| footnotes = {{notelist|group=infobox}}
| supply_limit = ₿21,000,000{{efn|name=supply}}
| timestamping = [[Proof of work]] (partial hash inversion)
| issuance_schedule = Decentralized (block reward)<br />Initially ₿50 per block, halved every 210,000 blocks
| block_time = 10 minutes
| block_reward = ₿3.125 ({{as of|2024|lc=y}})
| exchange_rate = Floating
| market_cap = <!--A reliable source is required -->
| using_countries = [[Bitcoin in El Salvador|El Salvador]]<ref name="BTCSVSept7FT">{{cite news |title=El Salvador's dangerous gamble on bitcoin |url=https://www.ft.com/content/c257a925-c864-4495-9149-d8956d786310 |date=7 September 2021 |access-date=7 September 2021 |work=[[Financial Times]] |department=The editorial board |archive-date=7 September 2021 |archive-url=https://web.archive.org/web/20210907081627/https://www.ft.com/content/c257a925-c864-4495-9149-d8956d786310 |url-status=live }}</ref>
}}
}}
{{Special characters}}
{{Special characters}}
'''Bitcoin''' (abbreviation: '''BTC'''; [[Currency symbol|sign]]: '''₿''') is the first [[Decentralized application|decentralized]] [[cryptocurrency]]. [[Node (networking)|Nodes]] in the [[peer-to-peer]] [[bitcoin network]] verify transactions through [[cryptography]] and record them in a public [[distributed ledger]], called a [[blockchain]], without central oversight. [[Consensus (computer science)|Consensus]] between nodes is achieved using a computationally intensive process based on [[proof of work]], called [[bitcoin mining|mining]], that guarantees the security of the bitcoin blockchain. Mining consumes increasing quantities of electricity and has been criticized for [[environmental effects of bitcoin|its environmental effects]].<ref>{{Cite news |last1=Huang |first1=Jon |last2=O’Neill |first2=Claire |last3=Tabuchi |first3=Hiroko |author3-link=Hiroko Tabuchi |date=3 September 2021 |title=Bitcoin Uses More Electricity Than Many Countries. How Is That Possible? |language=en-US |work=The New York Times |url=https://www.nytimes.com/interactive/2021/09/03/climate/bitcoin-carbon-footprint-electricity.html |access-date=26 October 2022 |issn=0362-4331 |archive-date=17 February 2023 |archive-url=https://web.archive.org/web/20230217105559/https://www.nytimes.com/interactive/2021/09/03/climate/bitcoin-carbon-footprint-electricity.html |url-status=live }}</ref>


Based on a [[free market]] ideology, bitcoin was invented in 2008 by [[Satoshi Nakamoto]], an unknown person.<ref name="whoissn">{{Cite news |last=S. |first=L. |date=2 November 2015 |title=Who is Satoshi Nakamoto? |newspaper=The Economist |url=https://www.economist.com/the-economist-explains/2015/11/02/who-is-satoshi-nakamoto |access-date=21 November 2023 |archive-date=22 November 2020 |archive-url=https://web.archive.org/web/20201122172929/https://www.economist.com/the-economist-explains/2015/11/02/who-is-satoshi-nakamoto |url-status=live }}</ref> Use of bitcoin as a [[currency]] began in 2009,<ref name="NY2011">{{Cite magazine |last=Davis |first=Joshua |date=10 October 2011 |title=The Crypto-Currency: Bitcoin and its mysterious inventor |url=https://www.newyorker.com/magazine/2011/10/10/the-crypto-currency |url-status=live |archive-url=https://web.archive.org/web/20141101014157/http://www.newyorker.com/magazine/2011/10/10/the-crypto-currency |archive-date=1 November 2014 |access-date=31 October 2014 |magazine=[[The New Yorker]]}}</ref> with the release of its [[open-source software|open-source implementation]].<ref name="Antonopoulos2014">{{Cite book |last=Antonopoulos|first= Andreas M. |title=Mastering Bitcoin: Unlocking Digital Crypto-Currencies |year=2014 |publisher=O'Reilly Media |isbn=978-1-4493-7404-4 |author-link=Andreas Antonopoulos}}</ref>{{rp|ch. 1}} In 2021, [[Bitcoin in El Salvador|El Salvador adopted it as legal tender]].<ref name=BTCSVSept7FT/> Bitcoin is currently used more as a [[store of value]] and less as a [[medium of exchange]] or [[unit of account]]. It is mostly seen as an [[investment]] and has been described by many scholars as an [[economic bubble]].<ref name="4Nobels">{{Cite news |last=Wolff-Mann |first=Ethan |date=27 April 2018 |title='Only good for drug dealers': More Nobel prize winners snub bitcoin |work=Yahoo Finance |url=https://finance.yahoo.com/news/good-drug-dealers-nobel-prize-winners-snub-bitcoin-184903784.html |url-status=live |access-date=7 June 2018 |archive-url=https://web.archive.org/web/20180612141128/https://finance.yahoo.com/news/good-drug-dealers-nobel-prize-winners-snub-bitcoin-184903784.html |archive-date=12 June 2018}}</ref> As bitcoin is [[pseudonym]]ous, [[Cryptocurrency and crime|its use by criminals]] has attracted the attention of regulators, leading to [[Legality of cryptocurrency by country or territory|its ban by several countries]] {{as of|2021|lc=yes}}.<ref name=SunYin2019>{{Cite journal |last1=Sun Yin |first1=Hao Hua |last2=Langenheldt |first2=Klaus |last3=Harlev |first3=Mikkel |last4=Mukkamala |first4=Raghava Rao |last5=Vatrapu |first5=Ravi |date=2 January 2019 |title=Regulating Cryptocurrencies: A Supervised Machine Learning Approach to De-Anonymizing the Bitcoin Blockchain |url=https://www.researchgate.net/publication/332118587 |journal=[[Journal of Management Information Systems]] |language=en |volume=36 |issue=1 |page=65 |doi=10.1080/07421222.2018.1550550 |s2cid=132398387 |issn=0742-1222 |access-date=29 November 2023 |archive-date=21 April 2024 |archive-url=https://web.archive.org/web/20240421113631/https://www.researchgate.net/publication/332118587_Regulating_Cryptocurrencies_A_Supervised_Machine_Learning_Approach_to_De-Anonymizing_the_Bitcoin_Blockchain |url-status=live }}</ref>
'''Bitcoin''' ('''₿''') is the world's first [[cryptocurrency]], a form of electronic cash.<ref name="primer">{{cite web |url = http://mercatus.org/sites/default/files/Brito_BitcoinPrimer.pdf |title = Bitcoin: A Primer for Policymakers |publisher = George Mason University |work = Mercatus Center |year = 2013 |accessdate = 22 October 2013 |author1 = Jerry Brito |author2 = Andrea Castillo |lastauthoramp = yes |deadurl = no |archiveurl = https://web.archive.org/web/20130921060724/http://mercatus.org/sites/default/files/Brito_BitcoinPrimer.pdf |archivedate = 21 September 2013 |df = dmy-all }}</ref>{{rp|3}}<ref name="4Nobels"/> It is the first decentralized [[digital currency]]: the system was designed to work without a [[central bank]] or single administrator.<ref name="primer" />{{rp|1}}<ref name="ieeesurvey" /> Bitcoins are sent from user to user on the [[peer-to-peer]] bitcoin network directly, without the need for intermediaries.<ref name="primer" />{{rp|4,5}} These transactions are verified by network [[Node (networking)|nodes]] through [[cryptography]] and recorded in a public [[distributed ledger]] called a [[#Blockchain|blockchain]]. Bitcoin was invented by an unknown person or group of people using the name [[Satoshi Nakamoto]]<ref name="whoissn">{{cite news |url = https://www.economist.com/blogs/economist-explains/2015/11/economist-explains-1 |title = Who is Satoshi Nakamoto? |last1 = S. |first1 = L. |date = 2 November 2015 |work = The Economist |accessdate = 23 September 2016 |archiveurl = https://web.archive.org/web/20160821154511/http://www.economist.com/blogs/economist-explains/2015/11/economist-explains-1 |archivedate = 21 August 2016 |deadurl = no |publisher = The Economist Newspaper Limited |df = dmy-all }}</ref> and released as [[open-source software]] in 2009.<ref name="NY2011">{{cite web |last = Davis |first = Joshua |title = The Crypto-Currency: Bitcoin and its mysterious inventor |url = http://www.newyorker.com/magazine/2011/10/10/the-crypto-currency |work = The New Yorker |date = 10 October 2011 |accessdate = 31 October 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20141101014157/http://www.newyorker.com/magazine/2011/10/10/the-crypto-currency |archivedate = 1 November 2014 |df = dmy-all }}</ref>


{{TOC LIMIT|4}}
Bitcoins are created as a reward for a process known as [[#Mining|mining]]. They can be exchanged for other currencies,<ref>{{cite news |title = What is Bitcoin? |url = http://money.cnn.com/infographic/technology/what-is-bitcoin/ |publisher = CNN Money |accessdate = 16 November 2015 |deadurl = no |archiveurl = https://web.archive.org/web/20151031113913/http://money.cnn.com/infographic/technology/what-is-bitcoin/ |archivedate = 31 October 2015 |df = dmy-all }}</ref> products, and services. Research produced by the [[University of Cambridge]] estimates that in 2017, there were 2.9 to 5.8 million unique users using a cryptocurrency wallet, most of them using bitcoin.<ref name="CU2017">{{cite web |last1 = Hileman |first1 = Garrick |last2 = Rauchs |first2 = Michel |title = Global Cryptocurrency Benchmarking Study |url = https://www.jbs.cam.ac.uk/fileadmin/user_upload/research/centres/alternative-finance/downloads/2017-global-cryptocurrency-benchmarking-study.pdf |publisher = Cambridge University |accessdate = 14 April 2017 |deadurl = no |archiveurl = https://web.archive.org/web/20170410130007/https://www.jbs.cam.ac.uk/fileadmin/user_upload/research/centres/alternative-finance/downloads/2017-global-cryptocurrency-benchmarking-study.pdf |archivedate = 10 April 2017 |df = dmy-all }}</ref>


==History==
Many economists and investors consider the bitcoin market to be a bubble. Bitcoin has also been criticized for its use in illegal transactions, its high electricity consumption, price volatility, and thefts from exchanges.

== Terminology ==

The word ''bitcoin'' was defined in a [[white paper]]<ref name="paper">{{cite web |url = https://bitcoin.org/bitcoin.pdf |title = Bitcoin: A Peer-to-Peer Electronic Cash System |date = 31 October 2008 |publisher = bitcoin.org |accessdate = 28 April 2014 |first = Satoshi |last = Nakamoto |deadurl = no |archiveurl = https://web.archive.org/web/20140320135003/https://bitcoin.org/bitcoin.pdf |archivedate = 20 March 2014 |df = dmy-all }}</ref> published on 31 October 2008.<ref name="ageofcr">{{cite book |last1 = Vigna |first1 = Paul |last2 = Casey |first2 = Michael J. |title = The Age of Cryptocurrency: How Bitcoin and Digital Money Are Challenging the Global Economic Order |date = January 2015 |publisher = St. Martin's Press |location = New York |isbn = 978-1-250-06563-6 |edition = 1 }}</ref> It is a [[Compound (linguistics)|compound]] of the words ''[[bit]]'' and ''[[coin]]''.<ref name=btox>{{cite web |title = bitcoin |url = http://www.oxforddictionaries.com/definition/english/bitcoin |publisher = [[OxfordDictionaries.com]] |accessdate = 28 December 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20150102041748/http://www.oxforddictionaries.com/definition/english/bitcoin |archivedate = 2 January 2015 |df = dmy-all }}</ref> Generally "bitcoin" is not capitalized, in the same manner as "dollar" and "euro" are not capitalized. "Bitcoin", capitalized, may refer to the technology and [[computer network|network]] and "bitcoin", lowercase, to refer to the currency.<ref name="capitalization">{{cite web |url = http://www.newyorker.com/tech/elements/the-bitcoin-boom |title = The Bitcoin Boom |publisher = Condé Nast |work = The New Yorker |date = 2 April 2013 |accessdate = 22 December 2013 |author = Bustillos, Maria |quote = Standards vary, but there seems to be a consensus forming around Bitcoin, capitalized, for the system, the software, and the network it runs on, and bitcoin, lowercase, for the currency itself. |deadurl = no |archiveurl = https://web.archive.org/web/20140727185121/http://www.newyorker.com/tech/elements/the-bitcoin-boom |archivedate = 27 July 2014 |df = dmy-all }}</ref><ref>{{cite news |last = Vigna |first = Paul |title = BitBeat: Is It Bitcoin, or bitcoin? The Orthography of the Cryptography |url = https://blogs.wsj.com/moneybeat/2014/03/14/bitbeat-is-it-bitcoin-or-bitcoin-the-orthography-of-the-cryptography |accessdate = 21 April 2014 |newspaper = [[Wall Street Journal|WSJ]] |date = 3 March 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20140419024119/http://blogs.wsj.com/moneybeat/2014/03/14/bitbeat-is-it-bitcoin-or-bitcoin-the-orthography-of-the-cryptography/ |archivedate = 19 April 2014 |df = dmy-all }}</ref>

One bitcoin can be subdivided into millibitcoin (mBTC), and satoshi (sat). Named in homage to bitcoin's creator, a ''satoshi'' is the smallest amount within bitcoin representing 0.00000001 bitcoins, one hundred millionth of a bitcoin.<ref name="satoshi unit" /> A ''millibitcoin'' equals 0.001 bitcoins, one thousandth of a bitcoin or 100,000 satoshis.<ref>{{cite news |url = http://edition.cnn.com/2014/06/18/business/bitcoin-your-way-to-a-double-espresso/ |title = Bitcoin your way to a double espresso |publisher = CNN |work = cnn.com |date = 9 July 2014 |accessdate = 23 April 2015 |author1 = Katie Pisa |author2 = Natasha Maguder |lastauthoramp = yes |deadurl = no |archiveurl = https://web.archive.org/web/20150618072429/http://edition.cnn.com/2014/06/18/business/bitcoin-your-way-to-a-double-espresso/ |archivedate = 18 June 2015 |df = dmy-all }}</ref>

[[Ticker symbol]]s used to represent bitcoin are BTC{{efn|name=BTCcode|{{as of | 2014}}, BTC is a commonly used code.

It does not conform to [[ISO 4217]] as BT is the country code of Bhutan, and ISO 4217 requires the first letter used in global commodities to be 'X'.}} and XBT.{{efn|name=XBTcode|{{as of | 2014}}, XBT, a code that conforms to ISO 4217 though is not officially part of it, is used by [[Bloomberg L.P.]],<ref>{{cite news |title = Bitcoin Ticker Available On Bloomberg Terminal For Employees |publisher = [[TechCrunch]] |url = https://techcrunch.com/2013/08/09/bitcoin-ticker-available-on-bloomberg-terminal/ |date = 9 August 2013 |author = Romain Dillet |accessdate = 2 November 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20141101232825/http://techcrunch.com/2013/08/09/bitcoin-ticker-available-on-bloomberg-terminal/ |archivedate = 1 November 2014 |df = dmy-all }}</ref> [[CNNMoney]],<ref>{{cite news |title = Bitcoin Composite Quote (XBT) |url = http://money.cnn.com/quote/quote.html?symb=XBT |publisher = CNN |work = CNN Money |accessdate = 2 November 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20141027100208/http://money.cnn.com/quote/quote.html?symb=xbt |archivedate = 27 October 2014 |df = dmy-all }}</ref> and [[xe.com]].<ref>{{cite web |title = XBT – Bitcoin |publisher = xe.com |accessdate = 2 November 2014 |url = http://www.xe.com/currency/xbt-bitcoin? |deadurl = no |archiveurl = https://web.archive.org/web/20141102111801/http://www.xe.com/currency/xbt-bitcoin |archivedate = 2 November 2014 |df = dmy-all }}</ref>}}

The [[Unicode]] character for bitcoin is ₿.<ref name=btcregs>{{cite web |url = https://www.loc.gov/law/help/bitcoin-survey/regulation-of-bitcoin.pdf |title = Regulation of Bitcoin in Selected Jurisdictions |publisher = The Law Library of Congress, Global Legal Research Center |date = January 2014 |accessdate = 26 August 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20141014012832/http://www.loc.gov/law/help/bitcoin-survey/regulation-of-bitcoin.pdf |archivedate = 14 October 2014 |df = dmy-all }}</ref>{{rp|2}} This was standardized in version 10.0 in June 2017. As with most new symbols, font support is very limited. Typefaces supporting it include Horta.

==Ideology==
Bitcoin is seen as having been politically or ideologically motivated starting from the white paper written by Satoshi Nakamoto. There he stated "The root problem with conventional currencies is all the trust that’s required to make it work. The central bank must be trusted not to debase the currency, but the history of fiat currencies is full of breaches of that trust."<ref name="BitIdeo">{{cite news |last1=Feuer |first1=Alan |title=The Bitcoin Ideology |url=https://www.nytimes.com/2013/12/15/sunday-review/the-bitcoin-ideology.html |accessdate=1 July 2018 |publisher=New York Times |date=14 December 2013}}</ref>

Early bitcoin supporters were considered to be [[libertarian]] or [[anarchist]] trying to remove currency from the control of governments. [[Roger Ver]] said "At first, almost everyone who got involved did so for philosophical reasons. We saw bitcoin as a great idea, as a way to separate money from the state."<ref name="BitIdeo"/>

Nigel Dodd argues in "The Social Life of Bitcoin" that the essence of the bitcoin ideology is to remove money from social, as well as governmental, control, and that "Bitcoin will succeed as ''money'' to the extent that it fails as an ''ideology''. The currency relies on that which the ideology underpinning it seeks to deny, namely, the dependence of money upon social relations, and upon trust.<ref name="DoddLSE">{{cite web |last1=Dodd |first1=Nigel |title=The social life of Bitcoin |url=http://eprints.lse.ac.uk/69229/1/Dodd_The%20social%20life%20of%20Bitcoin_author_2017%20LSERO.pdf |website=LSE Research Online |accessdate=1 July 2018 |date=2017}}</ref>

{{external media | width = 210px | float = right | video1 = [https://www.youtube.com/watch?v=XQqZ9b0S0BY The Declaration Of Bitcoin's Independence], BraveTheWorld, 4:38<ref name="DecInd"/>| accessdate =July 1, 2018 }}
Dodd shows the intensity of the ideological and political motivation for bitcoin by quoting a YouTube video, with Roger Ver, [[Jeff Berwick]], Kristov Atlas, Trace Meyer and other leaders of the bitcoin movement reading ''The Declaration of Bitcoin's Independence.'' The declaration includes the words "Bitcoin is inherently anti-establishment, anti-system, and anti-state. Bitcoin undermines governments and disrupts institutions because bitcoin is fundamentally humanitarian."<ref name="DoddLSE"/><ref name="DecInd">{{cite web |last1=Tourianski |first1=Julia |title=The Declaration Of Bitcoin's Independence |url=https://archive.org/details/DECLARATION_201508 |website=Archive.org |accessdate=1 July 2018}}</ref>

David Golumbia traces the influences on bitcoin ideology back to right-wing extremists such as the [[Liberty Lobby]] and the [[John Birch Society]] and their anti-Central Bank rhetoric. More recent influences include [[Ron Paul]] and [[Tea Party movement|Tea Party]]-style libertarianism.<ref name="Golumbia1">{{cite book |last1=Golumbia |first1=David |editor1-last=Lovink |editor1-first=Geert |title=Bitcoin as Politics: Distributed Right-Wing Extremism |date=2015 |publisher=Institute of Network Cultures, Amsterdam |isbn=978-90-822345-5-8 |pages=117-131 |url=https://poseidon01.ssrn.com/delivery.php?ID=638096082013126019075001030016090091053039023004022060096115026072001090091017090005100007032007024026014125106070028021015078045005010079051076027087082070020112088028013016000113122083084111125120107068127064026098006121014099115067086085066096065127&EXT=pdf}}</ref> [[Steve Bannon]] who owns a "good stake" in bitcoin, considers it to be "disruptive populism. It takes control back from central authorities. It’s revolutionary."<ref name="NYTBannon">{{cite news |last1=Peters |first1=Jeremy W. |last2=Popper |first2=Nathaniel |title=Stephen Bannon Buys Into Bitcoin |url=https://www.nytimes.com/2018/06/14/technology/steve-bannon-bitcoin.html |accessdate=1 July 2018 |publisher=New York Times |date=14 June 2018}}</ref>

== History ==
{{Main|History of bitcoin}}
{{Main|History of bitcoin}}
===Creation===
The domain name "bitcoin.org" was registered on 18 August 2008.<ref>{{cite news |last1=Bernard |first1=Zoë |title=Everything you need to know about Bitcoin, its mysterious origins, and the many alleged identities of its creator |url=http://www.businessinsider.com/bitcoin-history-cryptocurrency-satoshi-nakamoto-2017-12 |accessdate=15 June 2018 |work=Business Insider |date=2 December 2017}}</ref> In November 2008, a link to a paper authored by [[Satoshi Nakamoto]] titled ''Bitcoin: A Peer-to-Peer Electronic Cash System''<ref name="paper" /> was posted to a cryptography mailing list. Nakamoto implemented the bitcoin software as [[open source code]] and released it in January 2009.<ref>{{cite web |url = https://sourceforge.net/p/bitcoin/code/HEAD/tree/ |title = Bitcoin |author = Nakamoto, Satoshi |date = 3 January 2009 |deadurl = no |archiveurl = https://web.archive.org/web/20170721190347/https://sourceforge.net/p/bitcoin/code/HEAD/tree/ |archivedate = 21 July 2017 |df = dmy-all }}</ref><ref>{{cite web |url = http://www.mail-archive.com/cryptography@metzdowd.com/msg10142.html |author = Nakamoto, Satoshi |date = 9 January 2009 |title = Bitcoin v0.1 released |archiveurl = https://web.archive.org/web/20140326174921/http://www.mail-archive.com/cryptography%40metzdowd.com/msg10142.html |archivedate = 26 March 2014 |deadurl = no |df = }}</ref><ref name="NY2011" /> The identity of Nakamoto remains unknown.{{r|whoissn}}


===Background===
In January 2009, the bitcoin network was created when Nakamoto mined the first block of the chain, known as the ''genesis block''.<ref name="Wired:RFB">{{cite news |author = Wallace, Benjamin |title = The Rise and Fall of Bitcoin |url = https://www.wired.com/magazine/2011/11/mf_bitcoin/ |publisher = Wired |date = 23 November 2011 |accessdate = 13 October 2012 |archiveurl = https://web.archive.org/web/20131031043919/http://www.wired.com/magazine/2011/11/mf_bitcoin |archivedate = 31 October 2013 |deadurl = no |df = }}</ref><ref>{{cite web |title = Block 0&nbsp;– Bitcoin Block Explorer |url = http://blockexplorer.com/block/000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f |archiveurl = https://web.archive.org/web/20131015154613/http://blockexplorer.com/block/000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f |archivedate = 15 October 2013 |deadurl = no |df = }}</ref> Embedded in the coinbase of this block was the following text:
Before bitcoin, several [[digital cash|digital cash technologies]] were released, starting with [[David Chaum]]'s [[ecash]] in the 1980s.<ref name=Narayanan2017/> The idea that solutions to computational puzzles could have some value was first proposed by cryptographers [[Cynthia Dwork]] and [[Moni Naor]] in 1992.<ref name=Narayanan2017/> The concept was [[Multiple discovery|independently rediscovered]] by [[Adam Back]] who developed [[Hashcash]], a [[proof-of-work]] scheme for [[Anti-spam techniques|spam control]] in 1997.<ref name="Narayanan2017" /> The first proposals for distributed digital scarcity-based [[cryptocurrencies]] came from [[cypherpunk]]s [[Wei Dai]] (b-money) and [[Nick Szabo]] ([[bit gold]]) in 1998.<ref>{{Cite journal |last1=Tschorsch |first1=Florian |last2=Scheuermann |first2=Bjorn |date=2 March 2016 |title=Bitcoin and Beyond: A Technical Survey on Decentralized Digital Currencies |url=https://ieeexplore.ieee.org/document/7423672 |journal=IEEE Communications Surveys & Tutorials |volume=18 |issue=3 |pages=2084–2123 |doi=10.1109/COMST.2016.2535718 |s2cid=5115101 |issn=1553-877X |access-date=23 November 2023 |archive-date=19 November 2023 |archive-url=https://web.archive.org/web/20231119025114/http://ieeexplore.ieee.org/document/7423672 |url-status=live }}</ref> In 2004, [[Hal Finney (cypherpunk)|Hal Finney]] developed the first currency based on reusable proof of work.<ref>{{cite book |last1=Judmayer |first1=Aljosha |chapter=History of Cryptographic Currencies |date=2017 |chapter-url=https://link.springer.com/10.1007/978-3-031-02352-1_3 |title=Blocks and Chains |pages=15–18 |publisher=[[Springer Nature|Springer]] |language=en |doi=10.1007/978-3-031-02352-1_3 |isbn=978-3-031-01224-2 |last2=Stifter |first2=Nicholas |last3=Krombholz |first3=Katharina |last4=Weippl |first4=Edgar |series=Synthesis Lectures on Information Security, Privacy, and Trust |url=https://link.springer.com/book/10.1007/978-3-031-02352-1 |access-date=22 November 2023 |archive-date=22 November 2023 |archive-url=https://web.archive.org/web/20231122135006/https://link.springer.com/book/10.1007/978-3-031-02352-1 |url-status=live }}</ref> These various attempts were not successful:<ref name="Narayanan2017" /> Chaum's concept required centralized control and no banks wanted to sign on, Hashcash had no protection against [[double-spending]], while b-money and bit gold were not resistant to [[Sybil attack]]s.<ref name=Narayanan2017>{{Cite journal |last1=Narayanan |first1=Arvind |last2=Clark |first2=Jeremy |date=27 November 2017 |title=Bitcoin's academic pedigree |url=https://queue.acm.org/detail.cfm?id=3136559 |journal=[[Communications of the ACM]] |volume=60 |issue=12 |pages=36–45 |doi=10.1145/3132259 |s2cid=6425116 |issn=0001-0782 |access-date=22 November 2023 |archive-date=14 October 2023 |archive-url=https://web.archive.org/web/20231014120907/https://queue.acm.org/detail.cfm?id=3136559 |url-status=live }}</ref>
<blockquote>The Times 03/Jan/2009 Chancellor on brink of second bailout for banks.<ref name="NY2011" /></blockquote>
This note has been interpreted as both a timestamp and a comment on the instability caused by [[fractional-reserve banking]].<ref>{{cite book|last1=Pagliery|first1=Jose|title=Bitcoin: And the Future of Money|date=2014|publisher=Triumph Books|isbn=9781629370361|url=https://books.google.com.au/books?id=_-wuBAAAQBAJ|accessdate=20 January 2018|deadurl=no|archiveurl=https://web.archive.org/web/20180121071329/https://books.google.com.au/books?id=_-wuBAAAQBAJ|archivedate=21 January 2018}}</ref>{{rp|18}}


===2008–2009: Creation===
The receiver of the first bitcoin transaction was [[cypherpunk]] [[Hal Finney (cypherpunk)|Hal Finney]], who created the first [[Proof-of-work system#Reusable proof-of-work as e-money|reusable proof-of-work]] system (RPOW) in 2004.<ref>{{cite web |url=http://www.sfgate.com/technology/businessinsider/article/Here-s-The-Problem-With-The-New-Theory-That-A-4529573.php |title=Here's The Problem with the New Theory That A Japanese Math Professor Is The Inventor of Bitcoin |work=San Francisco Chronicle |accessdate=24 February 2015 |deadurl=no |archiveurl=https://web.archive.org/web/20150104063653/http://www.sfgate.com/technology/businessinsider/article/Here-s-The-Problem-With-The-New-Theory-That-A-4529573.php |archivedate=4 January 2015 |df= }}</ref> Finney downloaded the bitcoin software on its release date, and received 10 bitcoins from Nakamoto.<ref>{{Cite news |url = https://www.washingtonpost.com/blogs/the-switch/wp/2014/01/03/hal-finney-received-the-first-bitcoin-transaction-heres-how-he-describes-it/ |title = Hal Finney received the first Bitcoin transaction. Here's how he describes it. |last = Peterson |first = Andrea |work = The Washington Post |accessdate = |date = 3 January 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20150227213647/http://www.washingtonpost.com/blogs/the-switch/wp/2014/01/03/hal-finney-received-the-first-bitcoin-transaction-heres-how-he-describes-it/ |archivedate = 27 February 2015 |df = dmy-all }}</ref><ref>{{cite news |last1 = Popper |first1 = Nathaniel |title = Hal Finney, Cryptographer and Bitcoin Pioneer, Dies at 58 |url = https://www.nytimes.com/2014/08/31/business/hal-finney-cryptographer-and-bitcoin-pioneer-dies-at-58.html?_r=1 |accessdate = 2 September 2014 |work = NYTimes |date = 30 August 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20140903162835/http://www.nytimes.com/2014/08/31/business/hal-finney-cryptographer-and-bitcoin-pioneer-dies-at-58.html?_r=1 |archivedate = 3 September 2014 |df = dmy-all }}</ref> Other early cypherpunk supporters were creators of bitcoin predecessors: [[Wei Dai]], creator of ''b-money'', and [[Nick Szabo]], creator of ''[[bit gold]]''.<ref name="WallaceWired11">{{cite news |url = https://www.wired.com/magazine/2011/11/mf_bitcoin/ |title = The Rise and Fall of Bitcoin |work = Wired |date = 23 November 2011 |accessdate = 4 November 2013 |author = Wallace, Benjamin |deadurl = no |archiveurl = https://web.archive.org/web/20131104055936/http://www.wired.com/magazine/2011/11/mf_bitcoin/ |archivedate = 4 November 2013 |df = dmy-all }}</ref>
{{external media
| float = right
| width = 258px
| image1 = [https://www.thetimes03jan2009.com/wp-content/uploads/2015/03/genesis-block-newspaper-bitcoin.jpg Cover page of ''The Times'' 3 January 2009 showing the headline used in the genesis block]
}}
{{multiple image
| width = 90
| image1 = Bitcoin old.png
| image2 = Bitcoin.png
| footer = Bitcoin logos made by Satoshi Nakamoto in 2009 (left) and 2010 (right) [[Skeuomorph|depict bitcoins]] as [[gold coin|gold tokens]].
}}
The domain name ''bitcoin.org'' was registered on 18 August 2008.<ref>{{Cite news |last=Bernard |first=Zoë |date=2 December 2017 |title=Everything you need to know about Bitcoin, its mysterious origins, and the many alleged identities of its creator |work=Business Insider |url=http://www.businessinsider.com/bitcoin-history-cryptocurrency-satoshi-nakamoto-2017-12 |url-status=live |access-date=15 June 2018 |archive-url=https://web.archive.org/web/20180615010015/http://www.businessinsider.com/bitcoin-history-cryptocurrency-satoshi-nakamoto-2017-12 |archive-date=15 June 2018}}</ref> On 31 October 2008, a link to a [[white paper]] authored by [[Satoshi Nakamoto]] titled ''Bitcoin: A Peer-to-Peer Electronic Cash System'' was posted to a cryptography mailing list.<ref>{{Cite news |last=Finley |first=Klint |date=31 October 2018 |title=After 10 Years, Bitcoin Has Changed Everything—And Nothing |magazine=Wired |url=https://www.wired.com/story/after-10-years-bitcoin-changed-everything-nothing/ |url-status=live |access-date=9 November 2018 |archive-url=https://web.archive.org/web/20181105070656/https://www.wired.com/story/after-10-years-bitcoin-changed-everything-nothing/ |archive-date=5 November 2018}}</ref> Nakamoto implemented the bitcoin software as [[open-source software|open-source code]] and released it in January 2009.<ref name="NY2011" /> Nakamoto's identity remains unknown.{{r|whoissn}} All individual components of bitcoin originated in earlier academic literature.<ref name=Narayanan2017/> Nakamoto's innovation was their complex interplay resulting in the first decentralized, Sybil resistant, [[Byzantine fault]] tolerant digital cash system, that would eventually be referred to as the first blockchain.<ref name=Narayanan2017/><ref name="te20151031">{{Cite news |last=Economist Staff |date=31 October 2015 |title=Blockchains: The great chain of being sure about things |url=https://www.economist.com/news/briefing/21677228-technology-behind-bitcoin-lets-people-who-do-not-know-or-trust-each-other-build-dependable |url-status=live |newspaper=[[The Economist]] |archive-url=https://web.archive.org/web/20160703000844/http://www.economist.com/news/briefing/21677228-technology-behind-bitcoin-lets-people-who-do-not-know-or-trust-each-other-build-dependable |archive-date=3 July 2016 |access-date=18 June 2016 }}</ref> Nakamoto's paper was not [[peer review]]ed and was initially ignored by academics, who argued that it could not work.<ref name=Narayanan2017/>


On 3 January 2009, the bitcoin network was created when Nakamoto mined the starting block of the chain, known as the ''[[Genesis (blockchain)|genesis block]]''.<ref name="Wired:RFB">{{Cite magazine |last=Wallace, Benjamin |date=23 November 2011 |title=The Rise and Fall of Bitcoin |url=https://www.wired.com/2011/11/mf-bitcoin/ |url-status=live |magazine=Wired |archive-url=https://web.archive.org/web/20131031043919/http://www.wired.com/magazine/2011/11/mf_bitcoin |archive-date=31 October 2013 |access-date=13 October 2012}}</ref> Embedded in this block was the text "The Times 03/Jan/2009 Chancellor on brink of [[2009 United Kingdom bank rescue package|second bailout for banks]]", which is the date and headline of an issue of ''[[The Times]]'' newspaper.<ref name="NY2011" /> Nine days later, Hal Finney received the first bitcoin transaction: ten bitcoins from Nakamoto.<ref>{{Cite news |last=Popper |first=Nathaniel |date=30 August 2014 |title=Hal Finney, Cryptographer and Bitcoin Pioneer, Dies at 58 |work=[[The New York Times]] |url=https://www.nytimes.com/2014/08/31/business/hal-finney-cryptographer-and-bitcoin-pioneer-dies-at-58.html |url-status=live |access-date=2 September 2014 |archive-url=https://web.archive.org/web/20140903162835/http://www.nytimes.com/2014/08/31/business/hal-finney-cryptographer-and-bitcoin-pioneer-dies-at-58.html |archive-date=3 September 2014}}</ref> Wei Dai and Nick Szabo were also early supporters.<ref name="Wired:RFB" /> On May 22, 2010, the first known [[Financial transaction|commercial transaction]] using bitcoin occurred when programmer Laszlo Hanyecz bought two [[Papa John's]] pizzas for ₿10,000, in what would later be celebrated as "Bitcoin Pizza Day".<ref>{{cite news |last1=Cooper |first1=Anderson |title=Meet the man who spent millions worth of bitcoin on pizza |url=https://www.cbsnews.com/news/meet-the-man-who-spent-millions-worth-of-bitcoin-on-pizza-60-minutes-2019-05-16 |work=[[CBS News]] |date=16 May 2019 |access-date=8 December 2021 |archive-date=8 December 2021 |archive-url=https://web.archive.org/web/20211208180706/https://www.cbsnews.com/news/meet-the-man-who-spent-millions-worth-of-bitcoin-on-pizza-60-minutes-2019-05-16/ |url-status=live }}</ref>
Nakamoto is estimated to have mined 1 million bitcoins.<ref>{{cite news |last1 = McMillan |first1 = Robert |title = Who Owns the World's Biggest Bitcoin Wallet? The FBI |url = https://www.wired.com/2013/12/fbi_wallet/ |accessdate = 7 October 2016 |work = Wired |publisher = Condé Nast |deadurl = no |archiveurl = https://web.archive.org/web/20161021221609/https://www.wired.com/2013/12/fbi_wallet/ |archivedate = 21 October 2016 |df = dmy-all }}</ref> before disappearing in 2010, when he handed the network alert key and control of the [[Bitcoin Core]] code repository over to [[Gavin Andresen]]. Andresen later became lead developer at the [[Bitcoin Foundation]].<ref>{{cite web |last1 = Simonite |first1 = Tom |title = Meet Gavin Andresen, the most powerful person in the world of Bitcoin |url = https://www.technologyreview.com/s/527051/the-man-who-really-built-bitcoin/ |website = MIT Technology Review |accessdate = 6 December 2017 }}</ref><ref name="governance">{{cite news |last1 = Odell |first1 = Matt |title = A Solution To Bitcoin’s Governance Problem |url = https://techcrunch.com/2015/09/21/a-solution-to-bitcoins-governance-problem/ |accessdate = 24 January 2016 |work = TechCrunch |date = 21 September 2015 |deadurl = no |archiveurl = https://web.archive.org/web/20160126051521/http://techcrunch.com/2015/09/21/a-solution-to-bitcoins-governance-problem/ |archivedate = 26 January 2016 |df = dmy-all }}</ref> Andresen then sought to decentralize control. This left opportunity for controversy to develop over the future development path of bitcoin.<ref name="breakingup" /><ref name="governance" />


===2011 - 2012===
===2010–2012: Early growth===
[[Blockchain#Blockchain analysis|Blockchain analysts]] estimate that Nakamoto had mined about one million bitcoins<ref>{{Cite news |last=McMillan |first=Robert |title=Who Owns the World's Biggest Bitcoin Wallet? The FBI |magazine=Wired |url=https://www.wired.com/2013/12/fbi-wallet/ |url-status=live |access-date=7 October 2016 |archive-url=https://web.archive.org/web/20161021221609/https://www.wired.com/2013/12/fbi-wallet/ |archive-date=21 October 2016}}</ref> before disappearing in 2010 when he handed the network alert key and control of the [[Software repository|code repository]] over to [[Gavin Andresen]]. Andresen later became lead developer at the [[Bitcoin Foundation]],<ref>{{cite news |last=Simonite |first=Tom |title=Meet Gavin Andresen, the most powerful person in the world of Bitcoin |date=15 August 2014 |url=https://www.technologyreview.com/2014/08/15/12784/the-man-who-really-built-bitcoin |work=[[MIT Technology Review]] |access-date=22 November 2023 |archive-date=22 November 2023 |archive-url=https://web.archive.org/web/20231122163924/https://www.technologyreview.com/2014/08/15/12784/the-man-who-really-built-bitcoin |url-status=live }}</ref><ref>{{Cite news |last=Odell |first=Matt |date=21 September 2015 |title=A Solution To Bitcoin's Governance Problem |work=TechCrunch |url=https://techcrunch.com/2015/09/21/a-solution-to-bitcoins-governance-problem/ |url-status=live |access-date=24 January 2016 |archive-url=https://web.archive.org/web/20160126051521/http://techcrunch.com/2015/09/21/a-solution-to-bitcoins-governance-problem/ |archive-date=26 January 2016}}</ref> an [[List of bitcoin organizations|organization]] founded in September 2012 to promote bitcoin.<ref>{{Cite news |last=Bustillos |first=Maria |date=1 April 2013 |title=The Bitcoin Boom |magazine=The New Yorker |url=https://www.newyorker.com/tech/elements/the-bitcoin-boom |url-status=live |access-date=30 July 2018 |archive-url=https://web.archive.org/web/20180702064450/https://www.newyorker.com/tech/elements/the-bitcoin-boom |archive-date=2 July 2018}}</ref>
Prices were extremely volatile in 2011, starting at $0.30 per bitcoin, growing 1,656% for the year to $5.27. Prices rose to $31.50 on June 8, a 10,500% increase from January 1. Within a month the price had crashed to $11.00, a 65% decline. The next month if fell to $7.80, and in another month to $4.77, for an overall 85% decline in the ninety days from the June 8 high.<ref name="BitBubbles">{{cite news |last1=Purcell |first1=Lynn Sebastian |title=Bitcoin Bubbles: A History |url=https://seekingalpha.com/article/4132395-bitcoin-bubbles-history |accessdate=3 July 2018 |publisher=Seeking Alpha |date=17 December 2017}}</ref><ref name="Odata">{{cite web |title=Bitcoin Historical Prices |url=https://www.officialdata.org/bitcoin-price |website=OfficialData.org |accessdate=3 July 2018}}</ref>


After early "[[proof-of-concept]]" transactions, the first major users of bitcoin were [[black market]]s, such as the [[dark web]] [[Silk Road (marketplace)|Silk Road]]. During its 30 months of existence, beginning in February 2011, Silk Road exclusively accepted bitcoins as payment, transacting ₿9.9&nbsp;million, worth about $214&nbsp;million.<ref name=JEP/>{{rp|222}}
[[Litecoin]] was an early bitcoin spinoff or altcoin, starting in October 2011. Many altcoins have been created since.


===2013–2014: First regulatory actions===
In 2012 bitcoin prices started at $5.27 growing 153% to $13.30 for the year.<ref name="Odata"/> By January 9 the price had risen to $7.38, but then crashed by 49% over the next 16 days. The price then rose to $16.41 on August 17, but fell by 57% over the next three days.<ref name="MktWatch09022018">{{cite news |last1=French |first1=Sally |title=Here’s proof that this bitcoin crash is far from the worst the cryptocurrency has seen |url=https://www.marketwatch.com/story/heres-proof-that-this-bitcoin-crash-is-far-from-the-worst-the-cryptocurrency-has-seen-2018-02-09 |accessdate=3 July 2018 |publisher=Market Watch |date=9 February 2017}}</ref>
In March 2013, the US [[Financial Crimes Enforcement Network]] (FinCEN) established regulatory guidelines for "decentralized virtual currencies" such as bitcoin, classifying American bitcoin miners who sell their generated bitcoins as [[money services business]]es, subject to registration and other legal obligations.<ref>{{cite news |last=Lee |first=Timothy B. |date=19 March 2013 |title=US regulator Bitcoin Exchanges Must Comply With Money Laundering Laws |url=https://arstechnica.com/tech-policy/2013/03/us-regulator-bitcoin-exchanges-must-comply-with-money-laundering-laws/ |url-status=live |archive-url=https://web.archive.org/web/20131021203745/http://arstechnica.com/tech-policy/2013/03/us-regulator-bitcoin-exchanges-must-comply-with-money-laundering-laws/ |archive-date=21 October 2013 |access-date=28 July 2017 |work=[[Ars Technica]]}}</ref> In May 2013, US authorities seized the unregistered [[Cryptocurrency exchange|exchange]] [[Mt. Gox]].<ref>{{cite news |last=Dillet |first=Romain |title=Feds Seize Assets From Mt. Gox's Dwolla Account, Accuse It Of Violating Money Transfer Regulations |url=https://techcrunch.com/2013/05/16/mt-gox-dwolla-account-money-seizure/ |work=[[TechCrunch]] |url-status=live |archive-url=https://web.archive.org/web/20131009161856/http://techcrunch.com/2013/05/16/mt-gox-dwolla-account-money-seizure/ |archive-date=9 October 2013 |access-date=15 May 2013}}</ref> In June 2013, the US [[Drug Enforcement Administration]] seized ₿11.02 from a man attempting to use them to buy illegal substances. This marked the first time a government agency had seized bitcoins.<ref>{{Cite news |last=Sampson |first=Tim |year=2013 |title=U.S. government makes its first-ever Bitcoin seizure |work=The Daily Dot |url=http://www.dailydot.com/business/11-bitcoins-seized-government-dea/ |url-status=live |access-date=15 October 2013 |archive-url=https://web.archive.org/web/20130712010826/http://www.dailydot.com/business/11-bitcoins-seized-government-dea/ |archive-date=12 July 2013}}</ref> The FBI seized about ₿30,000 in October 2013 from Silk Road, following the arrest of its founder [[Ross Ulbricht]].<ref>{{Cite news |last=Hill |first=Kashmir |title=The FBI's Plan For The Millions Worth Of Bitcoins Seized From Silk Road |work=Forbes |url=https://www.forbes.com/sites/kashmirhill/2013/10/04/fbi-silk-road-bitcoin-seizure/ |url-status=live |archive-url=https://web.archive.org/web/20140502154935/http://www.forbes.com/sites/kashmirhill/2013/10/04/fbi-silk-road-bitcoin-seizure/ |archive-date=2 May 2014}}</ref>


In December 2013, the [[People's Bank of China]] prohibited Chinese financial institutions from using bitcoin.<ref>{{Cite news |last=Kelion, Leo |date=18 December 2013 |title=Bitcoin sinks after China restricts yuan exchanges |work=BBC News |url=https://www.bbc.co.uk/news/technology-25428866 |url-status=live |access-date=20 December 2013 |archive-url=https://web.archive.org/web/20131219214615/http://www.bbc.co.uk/news/technology-25428866 |archive-date=19 December 2013}}</ref> After the announcement, the value of bitcoin dropped,<ref>{{Cite news |date=6 December 2013 |title=China bans banks from bitcoin transactions |work=[[The Sydney Morning Herald]] |publisher=Reuters |url=https://www.smh.com.au/business/markets/currencies/china-bans-banks-from-bitcoin-transactions-20131206-2yugy.html |url-status=live |access-date=31 October 2014 |archive-url=https://web.archive.org/web/20140323102824/http://www.smh.com.au/business/markets/currencies/china-bans-banks-from-bitcoin-transactions-20131206-2yugy.html |archive-date=23 March 2014}}</ref> and [[Baidu]] no longer accepted bitcoins for certain services.<ref>{{Cite news |date=7 December 2013 |title=Baidu Stops Accepting Bitcoins After China Ban |work=Bloomberg |location=New York |url=https://www.bloomberg.com/news/2013-12-07/baidu-stops-accepting-bitcoins-after-china-ban.html |url-status=live |access-date=11 December 2013 |archive-url=https://web.archive.org/web/20131210214547/http://www.bloomberg.com/news/2013-12-07/baidu-stops-accepting-bitcoins-after-china-ban.html |archive-date=10 December 2013}}</ref> Buying real-world goods with any virtual currency had been illegal in China since at least 2009.<ref>{{cite web |date=29 June 2009 |title=China bars use of virtual money for trading in real goods |url=http://english.mofcom.gov.cn/aarticle/newsrelease/commonnews/200906/20090606364208.html |url-status=live |archive-url=https://web.archive.org/web/20131129184312/http://english.mofcom.gov.cn/aarticle/newsrelease/commonnews/200906/20090606364208.html |archive-date=29 November 2013 |access-date=10 January 2014 |publisher=English.mofcom.gov.cn}}</ref>
The Bitcoin Foundation was founded in September 2012 to "accelerate the global growth of bitcoin through standardization, protection, and promotion of the open source protocol". The founders included [[Gavin Andresen]] and [[Charlie Shrem]].<ref>{{Cite news|url=https://www.forbes.com/sites/jonmatonis/2012/09/27/bitcoin-foundation-launches-to-drive-bitcoins-advancement/#3fbfe7d1d868|title=Bitcoin Foundation Launches To Drive Bitcoin's Advancement|last=Matonis|first=Jon|work=Forbes|access-date=2017-05-20}}</ref>


===2013 - 2016===
===2015–2019===
Research produced by the [[University of Cambridge]] estimated that in 2017, there were 2.9 to 5.8 million unique users using a [[cryptocurrency wallet]], most of them using bitcoin.<ref>{{cite web |last1=Hileman |first1=Garrick |last2=Rauchs |first2=Michel |title=Global Cryptocurrency Benchmarking Study |url=https://www.jbs.cam.ac.uk/fileadmin/user_upload/research/centres/alternative-finance/downloads/2017-global-cryptocurrency-benchmarking-study.pdf |url-status=live |archive-url=https://web.archive.org/web/20170410130007/https://www.jbs.cam.ac.uk/fileadmin/user_upload/research/centres/alternative-finance/downloads/2017-global-cryptocurrency-benchmarking-study.pdf |archive-date=10 April 2017 |access-date=14 April 2017 |publisher=Cambridge University}}</ref> In August 2017, the [[SegWit]] software upgrade was activated. Segwit was intended to support the [[Lightning Network]] as well as improve [[scalability]].<ref>{{Cite news |last=Vigna |first=Paul |date=21 July 2017 |title=Bitcoin Rallies Sharply After Vote Resolves Bitter Scaling Debate |work=The Wall Street Journal |url=https://www.wsj.com/articles/bitcoin-rallies-sharply-after-vote-resolves-bitter-scaling-debate-1500656084 |access-date=21 November 2023 |archive-date=21 November 2023 |archive-url=https://web.archive.org/web/20231121164350/https://www.wsj.com/articles/bitcoin-rallies-sharply-after-vote-resolves-bitter-scaling-debate-1500656084 |url-status=live }}</ref> SegWit opponents, who supported larger blocks as a scalability solution, [[Fork (blockchain)|forked]] to create [[Bitcoin Cash]], one of many [[List of bitcoin forks|forks of bitcoin]].<ref>{{Cite news |last=Selena Larson |date=1 August 2017 |title=Bitcoin split in two, here's what that means |work=CNN Tech |publisher=Cable News Network |url=https://money.cnn.com/2017/08/01/technology/business/bitcoin-cash-new-currency/index.html |url-status=live |access-date=2 April 2018 |archive-url=https://web.archive.org/web/20180227214042/https://money.cnn.com/2017/08/01/technology/business/bitcoin-cash-new-currency/index.html |archive-date=27 February 2018}}</ref>
In 2013 prices started at $13.30 rising 5,691% to $770 by January 1, 2014.<ref name="Odata"/>


In December 2017, the first [[futures contract|futures]] on bitcoin was introduced by the [[Chicago Mercantile Exchange]] (CME).<ref>{{Cite web |url=https://www.cnbc.com/2017/12/17/worlds-largest-futures-exchange-set-to-launch-bitcoin-futures-sunday-night.html |title=Bitcoin debuts on the world’s largest futures exchange, and prices fall slightly |date=17 December 2017 |access-date=19 January 2024 |website=CNBC |last=Cheng |first=Evelyn |archive-date=18 January 2024 |archive-url=https://web.archive.org/web/20240118182719/https://www.cnbc.com/2017/12/17/worlds-largest-futures-exchange-set-to-launch-bitcoin-futures-sunday-night.html |url-status=live }}</ref>
In March 2013 the [[blockchain]] temporarily split into two independent chains with different rules. The two blockchains operated simultaneously for six hours, each with its own version of the transaction history. Normal operation was restored when the majority of the network downgraded to version 0.7 of the bitcoin software.<ref name="bug events">{{cite web |last=Lee |first=Timothy |url=https://arstechnica.com/business/2013/03/major-glitch-in-bitcoin-network-sparks-sell-off-price-temporarily-falls-23/ |title=Major glitch in Bitcoin network sparks sell-off; price temporarily falls 23% |publisher=arstechnica.com |date=11 March 2013 |accessdate=15 February 2015}}</ref> The [[Mt. Gox]] exchange briefly halted bitcoin deposits and the price dropped by 23% to $37<ref name="ArsFork">{{cite web|last=Lee|first=Timothy|title=Major glitch in Bitcoin network sparks sell-off; price temporarily falls 23%|url=https://arstechnica.com/business/2013/03/major-glitch-in-bitcoin-network-sparks-sell-off-price-temporarily-falls-23/|publisher=Arstechnica|date=12 March 2013 | archiveurl = https://www.webcitation.org/6G4e02Xd1 | archivedate = 2013-04-22| deadurl=no}}</ref><ref name="VergeFork">{{cite web|last=Blagdon|first=Jeff|title=Technical problems cause Bitcoin to plummet from record high, Mt. Gox suspends deposits|url=https://www.theverge.com/2013/3/12/4092898/technical-problems-cause-bitcoin-to-plummet-from-record-high|publisher=The Verge|date=12 March 2013 | archiveurl = https://www.webcitation.org/6G4e0aImv | archivedate = 2013-04-22| deadurl=no}}</ref> before recovering to previous level of approximately $48 in the following hours.<ref>{{cite web|title=Bitcoin Charts|url=http://bitcoincharts.com/charts/mtgoxUSD#rg60zczsg2013-03-12zeg2013-03-15ztgSzm1g10zm2g25zv | archiveurl = https://web.archive.org/web/20140509133404/http://bitcoincharts.com/charts/mtgoxUSD | archivedate = 2014-05-09| deadurl=no}}</ref>


In February 2018, the price crashed after China imposed a complete ban on Bitcoin trading.<ref>{{Cite news |last=French |first=Sally |date=9 February 2017 |title=Here's proof that this bitcoin crash is far from the worst the cryptocurrency has seen |publisher=Market Watch |url=https://www.marketwatch.com/story/heres-proof-that-this-bitcoin-crash-is-far-from-the-worst-the-cryptocurrency-has-seen-2018-02-09 |url-status=live |access-date=3 July 2018 |archive-url=https://web.archive.org/web/20180703220246/https://www.marketwatch.com/story/heres-proof-that-this-bitcoin-crash-is-far-from-the-worst-the-cryptocurrency-has-seen-2018-02-09 |archive-date=3 July 2018}}</ref> The percentage of bitcoin trading in the Chinese [[renminbi]] fell from over 90% in September 2017 to less than 1% in June 2018.<ref>{{Cite news |date=7 July 2018 |title=RMB Bitcoin trading falls below 1 pct of world total |publisher=Xinhuanet |agency=[[Xinhua]] |url=http://www.xinhuanet.com/english/2018-07/07/c_137308879.htm |url-status=live |access-date=10 July 2018 |archive-url=https://web.archive.org/web/20180710225218/http://www.xinhuanet.com/english/2018-07/07/c_137308879.htm |archive-date=10 July 2018}}</ref> During the same year, Bitcoin prices were negatively affected by several hacks or thefts from cryptocurrency exchanges.<ref>{{Cite news |last=Chavez-Dreyfuss |first=Gertrude |date=3 July 2018 |title=Cryptocurrency exchange theft surges in first half of 2018: report |work=Reuters |url=https://www.reuters.com/article/us-crypto-currencies-ciphertrace/cryptocurrency-exchange-theft-surges-in-first-half-of-2018-report-idUSKBN1JT1Q5 |url-status=live |access-date=10 July 2018 |archive-url=https://web.archive.org/web/20180704120854/https://www.reuters.com/article/us-crypto-currencies-ciphertrace/cryptocurrency-exchange-theft-surges-in-first-half-of-2018-report-idUSKBN1JT1Q5 |archive-date=4 July 2018}}</ref>
The US [[FinCEN|Financial Crimes Enforcement Network (FinCEN)]] established regulatory guidelines for "decentralized virtual currencies" such as bitcoin, classifying American bitcoin miners who sell their generated bitcoins as Money Service Businesses (MSBs), that are subject to registration or other legal obligations.<ref name="ArsFinCEN">{{cite web|last=Lee|first=Timothy|title=US regulator Bitcoin Exchanges Must Comply With Money Laundering Laws|url=https://arstechnica.com/tech-policy/2013/03/us-regulator-bitcoin-exchanges-must-comply-with-money-laundering-laws/|publisher=Arstechnica|date=20 March 2013|quote=Bitcoin miners must also register if they trade in their earnings for dollars. | archiveurl = https://web.archive.org/web/20131021203745/http://arstechnica.com:80/tech-policy/2013/03/us-regulator-bitcoin-exchanges-must-comply-with-money-laundering-laws/ | archivedate = 2013-10-21| deadurl=no}}</ref><ref name="Finextra1">{{cite web|title=US govt clarifies virtual currency regulatory position|url=http://www.finextra.com/News/FullStory.aspx?newsitemid=24645|publisher=Finextra|date=19 March 2013 | archiveurl = https://web.archive.org/web/20140326183202/http://www.finextra.com/News/FullStory.aspx?newsitemid=24645 | archivedate = 2014-03-26| deadurl=no}}</ref><ref name="FinCEN1">{{cite web|title=Application of FinCEN's Regulations to Persons Administering, Exchanging, or Using Virtual Currencies|url=http://www.fincen.gov/statutes_regs/guidance/pdf/FIN-2013-G001.pdf|publisher=Department of the Treasury Financial Crimes Enforcement Network|accessdate=19 March 2013}}</ref>


===2020–present===
In April, payment processors [[BitInstant]] and Mt. Gox experienced processing delays due to insufficient capacity<ref>Roose, Kevin (8 April 2013) {{cite web |url=http://nymag.com/daily/intelligencer/2013/04/inside-the-bitcoin-bubble-bitinstants-ceo.html |title=Inside the Bitcoin Bubble: BitInstant's CEO&nbsp;– Daily Intelligencer | archiveurl = https://web.archive.org/web/20140409031731/http://nymag.com/daily/intelligencer/2013/04/inside-the-bitcoin-bubble-bitinstants-ceo.html | archivedate = 2014-04-09| deadurl=no}}. Nymag.com. Retrieved on 20 April 2013.</ref> resulting in the bitcoin price dropping from $266 to $76 before returning to $160 within six hours.<ref>{{cite web|url=http://bitcoincharts.com/charts/mtgoxUSD|title=Bitcoin Exchange Rate|publisher=Bitcoinscharts.com|accessdate=2013-08-15| archiveurl = https://www.webcitation.org/68eGWrjWE | archivedate = 2012-06-24| deadurl=no}}</ref>
[[File:Bitcoin usd price.svg|thumb|Bitcoin price in US dollars]]
In 2020, some major companies and institutions started to acquire bitcoin: [[MicroStrategy]] invested $250 million in bitcoin as a [[Treasury management|treasury reserve asset]],<ref>{{Cite news |date=13 September 2021 |title=MicroStrategy buys another $250m worth of bitcoin in hope of 100X price growth |url=https://www.independent.co.uk/tech/microstrategy-bitcoin-crypto-price-prediction-b1919178.html |access-date=22 November 2023 |work=[[The Independent]] |first=Anthony |last=Cuthbertson |language=en |archive-date=22 November 2023 |archive-url=https://web.archive.org/web/20231122163924/https://www.independent.co.uk/tech/microstrategy-bitcoin-crypto-price-prediction-b1919178.html |url-status=live }}</ref> [[Square, Inc.]], $50 million,<ref>{{cite news |author=Oliver Effron |title=Square just bought $50 million in bitcoin |url=https://www.cnn.com/2020/10/08/business/square-bitcoin-crypto-investment/index.html |access-date=22 October 2020 |work=CNN |archive-date=24 October 2020 |archive-url=https://web.archive.org/web/20201024101610/https://www.cnn.com/2020/10/08/business/square-bitcoin-crypto-investment/index.html |url-status=live }}</ref> and [[MassMutual]], $100 million.<ref>{{cite news |url=https://www.bloomberg.com/news/articles/2020-12-10/169-year-old-insurer-massmutual-invests-100-million-in-bitcoin |title=169-Year-Old MassMutual Invests $100 Million in Bitcoin |date=11 December 2020 |work=Bloomberg |access-date=26 December 2020 |author=Olga Kharif |archive-date=19 December 2020 |archive-url=https://web.archive.org/web/20201219220543/https://www.bloomberg.com/news/articles/2020-12-10/169-year-old-insurer-massmutual-invests-100-million-in-bitcoin |url-status=live }}</ref> In November 2020, [[PayPal]] added support for bitcoin in the US.<ref>{{cite news |date=13 November 2020 |title=PayPal says all users in US can now buy, hold and sell cryptocurrencies |url=https://techcrunch.com/2020/11/12/paypal-says-all-users-in-u-s-can-now-buy-hold-and-sell-cryptocurrencies/ |access-date=26 November 2020 |work=Techcrunch |archive-date=24 November 2020 |archive-url=https://web.archive.org/web/20201124050031/https://techcrunch.com/2020/11/12/paypal-says-all-users-in-u-s-can-now-buy-hold-and-sell-cryptocurrencies/ |url-status=live }}</ref>


In February 2021, Bitcoin's [[market capitalization]] reached $1 trillion for the first time.<ref>{{Cite news |last1=Chavez-Dreyfuss |first1=Gertrude |last2=Wilson |first2=Tom |date=19 February 2021 |title=Bitcoin hits $1 trillion market cap, surges to fresh all-time peak |language=en-US |work=Reuters |url=https://www.reuters.com.article/idUSKBN2AJ0GC/ |access-date=24 November 2023}}</ref> In November 2021, the [[Taproot (fork)|Taproot]] [[soft-fork]] upgrade was activated, adding support for [[Schnorr signature]]s, improved functionality of [[smart contract]]s and [[Lightning Network]].<ref>{{cite news |last=Sigalos |first=MacKenzie |date=14 November 2021 |title=Bitcoin's biggest upgrade in four years just happened – here's what changes |url=https://www.cnbc.com/2021/11/14/bitcoin-taproot-upgrade-what-it-means-for-investors.html |access-date=15 November 2021 |work=CNBC |archive-date=14 November 2021 |archive-url=https://web.archive.org/web/20211114215032/https://www.cnbc.com/2021/11/14/bitcoin-taproot-upgrade-what-it-means-for-investors.html |url-status=live }}</ref> Before, Bitcoin only used a custom [[elliptic curve cryptography|elliptic curve]] with the [[ECDSA]] algorithm to produce [[digital signature|signatures]].<ref>{{Cite book |last1=Van Hijfte |first1=Stijn |title=Blockchain Platforms: A Look at the Underbelly of Distributed Platforms |publisher=Morgan & Claypool Publishers |year=2020 |isbn=978-1681738925}}</ref>{{rp|101}} In September 2021, Bitcoin became [[legal tender]] in [[Bitcoin in El Salvador|El Salvador]], alongside the US dollar.<ref name=BTCSVSept7FT/> In October 2021, the first bitcoin futures [[Exchange-traded fund]] (ETF), called BITO, from [[ProShares]] was approved by the [[U.S. Securities and Exchange Commission|SEC]] and listed on the [[Chicago Mercantile Exchange|CME]].<ref>{{Cite web |url=https://www.wsj.com/articles/a-bitcoin-etf-is-almost-here-what-does-that-mean-for-investors-11634376601 |title=A Bitcoin ETF Is Here. What Does That Mean for Investors? |date=19 October 2021 |access-date=11 January 2024 |website=The Wall Street Journal |last=Wursthorn |first=Michael |url-access=subscription |archive-date=10 January 2024 |archive-url=https://web.archive.org/web/20240110200308/https://www.wsj.com/articles/a-bitcoin-etf-is-almost-here-what-does-that-mean-for-investors-11634376601 |url-status=live }}</ref>
The bitcoin price rose to $259 on April 10, but then crashed by 83% over the next 3 days.<ref name="MktWatch09022018"/>


In May and June 2022, the bitcoin price fell following the collapses of [[Terra (blockchain)|TerraUSD]], a [[stablecoin]],<ref>{{cite news|last=Browne|first=Ryan|date=10 May 2022|title=Bitcoin investors are panicking as a controversial crypto experiment unravels|url=https://www.cnbc.com/2022/05/10/bitcoin-btc-investors-panic-as-terrausd-ust-sinks-below-1-peg.html|work=CNBC|access-date=11 May 2022|archive-date=11 May 2022|archive-url=https://web.archive.org/web/20220511021259/https://www.cnbc.com/2022/05/10/bitcoin-btc-investors-panic-as-terrausd-ust-sinks-below-1-peg.html|url-status=live}}</ref> and the [[Celsius Network]], a cryptocurrency loan company.<ref>{{cite news|last1=Milmo|first1=Dan|title=Bitcoin value slumps below $20,000 in cryptocurrencies turmoil|url=https://www.theguardian.com/technology/2022/jun/18/bitcoin-value-falls-cryptocurrency-markets-turmoil|access-date=19 June 2022|work=The Guardian|date=18 June 2022|language=en|archive-date=18 June 2022|archive-url=https://web.archive.org/web/20220618231120/https://www.theguardian.com/technology/2022/jun/18/bitcoin-value-falls-cryptocurrency-markets-turmoil|url-status=live}}</ref><ref>{{cite news|last=Yaffe-Bellany|first=David|date=13 June 2022|title=Celsius Network Leads Crypto Markets Into Another Free Fall|url=https://www.nytimes.com/2022/06/13/technology/bitcoin-ether-price.html|work=The New York Times|access-date=14 June 2022|archive-date=14 June 2022|archive-url=https://web.archive.org/web/20220614030021/https://www.nytimes.com/2022/06/13/technology/bitcoin-ether-price.html|url-status=live}}</ref>
On 15 May 2013, the US authorities seized accounts associated with Mt. Gox after discovering that it had not registered as a [[money transmitter]] with FinCEN in the US.<ref>{{cite web|last=Dillet|first=Romain|title=Feds Seize Assets From Mt. Gox's Dwolla Account, Accuse It Of Violating Money Transfer Regulations|url=https://techcrunch.com/2013/05/16/mt-gox-dwolla-account-money-seizure/|accessdate=2013-05-15| archiveurl = https://web.archive.org/web/20131009161856/http://techcrunch.com:80/2013/05/16/mt-gox-dwolla-account-money-seizure/ | archivedate = 2013-10-09| deadurl=no}}</ref><ref name="ABA FINCEN">{{cite web |title=Some basic rules for using 'bitcoin' as virtual money |url=http://www.abajournal.com/magazine/article/some_basic_rules_for_using_bitcoin_as_virtual_money/ |publisher=American Bar Association |year=2013 |accessdate=2013-06-26 |last=Berson |first=Susan A.| archiveurl = https://web.archive.org/web/20131029185546/http://www.abajournal.com/magazine/article/some_basic_rules_for_using_bitcoin_as_virtual_money/ | archivedate = 2013-10-29| deadurl=no}}</ref>


In 2023, ordinals—[[non-fungible token]]s (NFTs)—on Bitcoin, went live.<ref>{{Cite journal |last=Behrendt |first=Philipp |date=2023 |title=Taxation of the New Age: New Guidance for the World of Digital Assets |url=https://heinonline.org/HOL/Page?handle=hein.journals/jtaxpp25&id=105&div=&collection= |journal=Journal of Tax Practice & Procedure |volume=25 |pages=47 |access-date=21 November 2023 |archive-date=21 November 2023 |archive-url=https://web.archive.org/web/20231121164911/https://heinonline.org/HOL/Page?handle=hein.journals/jtaxpp25&id=105&div=&collection= |url-status=live }}</ref> In January 2024, the first 11 US [[spot market|spot]] bitcoin [[exchange-traded fund|ETF]]s began trading, offering direct exposure to bitcoin for the first time on American stock exchanges.<ref>{{Cite news |last=Schmitt |first=Will |date=12 January 2024 |title=Bitcoin trading volumes surge after debut of long-awaited US ETFs |url=https://www.ft.com/content/f30ece62-0f1c-492a-8ccd-63ec9730573c |access-date=12 January 2024 |work=Financial Times |archive-date=12 January 2024 |archive-url=https://web.archive.org/web/20240112025105/https://www.ft.com/content/f30ece62-0f1c-492a-8ccd-63ec9730573c |url-status=live }}</ref><ref>{{cite news|last1=Lang|first1=Hannah|title=US bitcoin ETFs see $4.6B in volume in first day of trading|url=https://www.reuters.com/technology/spot-bitcoin-etfs-start-trading-big-boost-crypto-industry-2024-01-11/|access-date=12 January 2024|work=Reuters|date=11 January 2024|language=en}}</ref> As of June 2023 River Financial estimated that Bitcoin had 81.7 million users, about 1% of the global population.<ref>{{cite web |title=As banks buy up bitcoins, who else are the 'Bitcoin whales'? |website=BBC Home |date=2024-03-01 |url=https://www.bbc.com/news/technology-68434579 |access-date=2024-03-14}}</ref>
On 23 June 2013, the US [[Drug Enforcement Administration]] listed 11.02 bitcoins as a seized asset in a [[United States Department of Justice]] seizure notice pursuant to 21 U.S.C. § 881.<ref>{{cite web|last=Cohen|first=Brian|title=Users Bitcoins Seized by DEA|url=http://letstalkbitcoin.com/users-bitcoins-seized-by-dea/|accessdate=2013-10-14| archiveurl = https://web.archive.org/web/20131009062454/http://letstalkbitcoin.com:80/users-bitcoins-seized-by-dea/ | archivedate = 2013-10-09| deadurl=no}}</ref> This marked the first time a government agency seized bitcoin.<ref>{{cite web|publisher=El Cuerpo Nacional de Policía|title=The National Police completes the second phase of the operation "Ransomware"|url=https://translate.google.com/translate?sl=es&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fwww.policia.es%2Fprensa%2F20130927_1.html|accessdate=2013-10-14}}</ref><ref>{{cite web
|title=U.S. government makes its first-ever Bitcoin seizure|url=http://www.dailydot.com/business/11-bitcoins-seized-government-dea/ |publisher=The Daily Dot |year=2013 |accessdate=2013-10-15 |last=Sampson |first=Tim| archiveurl = https://www.webcitation.org/6Hl0y7teb |archivedate = 2013-06-30| deadurl=no}}</ref>


==Design==
The FBI seized about 26,000 bitcoins in October 2013 from darknet website [[Silk Road (marketplace)|Silk Road]] during the arrest of [[Ross William Ulbricht]].<ref>{{cite web|title=After Silk Road seizure, FBI Bitcoin wallet identified and pranked|url=http://www.zdnet.com/after-silk-road-seizure-fbi-bitcoin-wallet-identified-and-pranked-7000021603/| archiveurl = https://web.archive.org/web/20140405173339/http://www.zdnet.com/after-silk-road-seizure-fbi-bitcoin-wallet-identified-and-pranked-7000021603/ | archivedate = 2014-04-05| deadurl=no}}</ref><ref>{{cite web|url=http://blockchain.info/address/1F1tAaz5x1HUXrCNLbtMDqcw6o5GNn4xqX|title=Silkroad Seized Coins| archiveurl = https://www.webcitation.org/6MUFj8Kcn | archivedate = 2014-01-09| deadurl=no}}</ref><ref>{{cite news|url=https://www.forbes.com/sites/kashmirhill/2013/10/04/fbi-silk-road-bitcoin-seizure/|title=The FBI's Plan For The Millions Worth Of Bitcoins Seized From Silk Road | work=Forbes | first=Kashmir|last=Hill| archiveurl = https://web.archive.org/web/20140502154935/http://www.forbes.com/sites/kashmirhill/2013/10/04/fbi-silk-road-bitcoin-seizure/ | archivedate = 2014-05-02| deadurl=no}}</ref>
{{Main|Bitcoin protocol}}


===Units and divisibility===
Bitcoin's price rose to $755 on 19 November and crashed by 50% to $378 the same day. On 30 November 2013 the price reached $1,163 before starting a long-term crash, declining by 87% to $152 in January 2015.<ref name="MktWatch09022018"/>
The [[unit of account]] of the bitcoin system is the ''bitcoin''. It is most commonly represented with the [[currency symbol|symbol]] ₿<ref name="unicode-10" /> and the [[currency code]] BTC. However, the BTC code does not conform to [[ISO 4217]] as BT is the country code of Bhutan,<ref name="ssrn.3383734">{{Cite journal |last=Alexander |first=Carol |last2=Imeraj |first2=Arben |date=2019 |title=Introducing the BITIX: The Bitcoin Fear Gauge |url=https://www.ssrn.com/abstract=3383734 |journal=[[SSRN Electronic Journal]] |language=en |doi=10.2139/ssrn.3383734 |issn=1556-5068|quote=XBT satisfies the norm ‘ISO 4217’ by the International Organisation for Standardisation (ISO) as BTC goes against the name of Bhutan’s currency. In general, transaction instruments that are not national currencies, like gold or silver, begin with an X. However, the symbol XBT is not officially recognised by ISO.}}</ref> and ISO 4217 requires the first letter used in global commodities to be 'X'.<ref name="ssrn.3383734"/> XBT, a code that conforms to [[ISO 4217]] though not officially part of it,<ref name="ssrn.3383734"/> is used by [[Bloomberg L.P.]]<ref>{{Cite news |last=Romain Dillet |date=9 August 2013 |title=Bitcoin Ticker Available On Bloomberg Terminal For Employees |work=[[TechCrunch]] |url=https://techcrunch.com/2013/08/09/bitcoin-ticker-available-on-bloomberg-terminal/ |url-status=live |access-date=2 November 2014 |archive-url=https://web.archive.org/web/20141101232825/http://techcrunch.com/2013/08/09/bitcoin-ticker-available-on-bloomberg-terminal/ |archive-date=1 November 2014}}</ref>


No uniform [[capitalization]] convention exists; some sources use ''Bitcoin'', capitalized, to refer to the technology and [[computer network|network]], and ''bitcoin'', lowercase, for the unit of account.<ref>{{Cite magazine |last=Bustillos, Maria |date=2 April 2013 |title=The Bitcoin Boom |url=https://www.newyorker.com/tech/elements/the-bitcoin-boom |url-status=live |magazine=[[The New Yorker]] |archive-url=https://web.archive.org/web/20140727185121/http://www.newyorker.com/tech/elements/the-bitcoin-boom |archive-date=27 July 2014 |access-date=22 December 2013}}</ref> The ''[[Cambridge Advanced Learner's Dictionary]]'' and the ''[[Oxford Advanced Learner's Dictionary]]'' use the capitalized and lowercase variants without distinction.<ref>[https://www.oxfordlearnersdictionaries.com/definition/english/bitcointm?q=bitcoin Bitcoin], ''[[Oxford Advanced Learner's Dictionary]]''</ref><ref>[https://dictionary.cambridge.org/dictionary/english/bitcoin bitcoin] {{Webarchive|url=https://web.archive.org/web/20220503092252/http://dictionary.cambridge.org/dictionary/english/bitcoin |date=3 May 2022 }}, ''[[Cambridge Advanced Learner's Dictionary]]''</ref>
On 5 December 2013, the [[People's Bank of China]] prohibited Chinese financial institutions from using bitcoins.<ref name="ccontrols">{{cite news |url=http://www.bbc.co.uk/news/technology-25428866 |title=Bitcoin sinks after China restricts yuan exchanges |publisher=BBC |work=bbc.com |date=18 December 2013 |accessdate=20 December 2013 |author=Kelion, Leo}}</ref> After the announcement, the value of bitcoins dropped,<ref>{{cite news |date=6 December 2013 |url=http://www.smh.com.au/business/markets/currencies/china-bans-banks-from-bitcoin-transactions-20131206-2yugy.html |title=China bans banks from bitcoin transactions |work=[[The Sydney Morning Herald]] |publisher=Reuters |accessdate=31 October 2014}}</ref> and Baidu no longer accepted bitcoins for certain services.<ref name="bloomberg">{{cite news |url=https://www.bloomberg.com/news/2013-12-07/baidu-stops-accepting-bitcoins-after-china-ban.html |title=Baidu Stops Accepting Bitcoins After China Ban |work=Bloomberg |location=New York |date=7 December 2013 |accessdate=11 December 2013}}</ref> Buying real-world goods with any virtual currency had been illegal in China since at least 2009.<ref>{{cite web |url=http://english.mofcom.gov.cn/aarticle/newsrelease/commonnews/200906/20090606364208.html |title=China bars use of virtual money for trading in real goods |publisher=English.mofcom.gov.cn |date=29 June 2009 |accessdate=10 January 2014}}</ref>


One bitcoin is divisible to eight decimal places.<ref name="Antonopoulos2014" />{{rp|ch. 5}} Units for smaller amounts of bitcoin are the millibitcoin (mBTC), equal to {{frac|1|1000}} bitcoin, and the satoshi{{efn|name=satoshi|Named after [[Satoshi Nakamoto]].}} (sat), representing {{frac|1|{{val|100000000}}}} (one hundred millionth) bitcoin, the smallest amount possible.<ref name="satoshi unit" /> 100,000 satoshis are one mBTC.<ref>{{Cite news |last1=Katie Pisa |last2=Natasha Maguder |date=9 July 2014 |title=Bitcoin your way to a double espresso |work=CNN |url=http://edition.cnn.com/2014/06/18/business/bitcoin-your-way-to-a-double-espresso/ |url-status=live |access-date=23 April 2015 |archive-url=https://web.archive.org/web/20150618072429/http://edition.cnn.com/2014/06/18/business/bitcoin-your-way-to-a-double-espresso/ |archive-date=18 June 2015 }}</ref>
In 2014 prices started at $770 and fell 59% to $314 for the year.<ref name="Odata"/>


===Blockchain===
In February 2014 the Mt. Gox exchange, the largest bitcoin exchange at the time, said that 850,000 bitcoins had been stolen from its customers, amounting to almost $500 million. Bitcoin's price fell by almost half, from $867 to $439 (a 49% drop). Prices remained low until late 2016.
{{further|Blockchain#Structure and design}}
As a [[Decentralization|decentralized]] system, bitcoin operates without a central authority or single administrator,<ref name=Gervais2014>{{Cite journal |last1=Gervais |first1=Arthur |last2=Karame |first2=Ghassan O. |last3=Capkun |first3=Vedran |last4=Capkun |first4=Srdjan |date=May 2014 |title=Is Bitcoin a Decentralized Currency? |url=https://ieeexplore.ieee.org/document/6824541 |journal=[[IEEE Security & Privacy]] |volume=12 |issue=3 |pages=54–60 |doi=10.1109/MSP.2014.49 |s2cid=13948781 |issn=1540-7993 |access-date=22 November 2023 |archive-date=19 November 2023 |archive-url=https://web.archive.org/web/20231119101600/https://ieeexplore.ieee.org/document/6824541/ |url-status=live }}</ref> so that anyone can create a new bitcoin address and transact without needing any approval.{{r|Antonopoulos2014|page=ch. 1}} This is accomplished through a specialized [[distributed ledger]] called a ''[[blockchain]]'' that records bitcoin transactions.{{r|econbc}}


The blockchain is implemented as an ordered list of ''blocks''. Each block contains a [[SHA-256]] [[Cryptographic hash function|hash]] of the previous block,<ref name="econbc" /> chaining them in chronological order.<ref name="Antonopoulos2014" />{{rp|ch. 7}}<ref name="econbc" /> The blockchain is maintained by a [[peer-to-peer]] network.<ref name=JEP/>{{rp|215–219}} Individual blocks, public addresses, and transactions within blocks are public information, and can be examined using a blockchain explorer.<ref>{{Cite web| url=https://nvlpubs.nist.gov/nistpubs/ir/2021/NIST.IR.8301.pdf| publisher=National Institute of Standards Technology (NIST)| access-date=29 December 2022| title=Blockchain Networks: Token Design and Management Overview| page=32| archive-date=24 December 2022| archive-url=https://web.archive.org/web/20221224003108/https://nvlpubs.nist.gov/nistpubs/ir/2021/NIST.IR.8301.pdf| url-status=live}}</ref>
In 2015 prices started at $314 and rose 38% to $434 for the year. In 2016 prices rose 130% to $998 on January 1, 2017.<ref name="Odata"/>


Nodes validate and broadcast transactions, each maintaining a copy of the blockchain for ownership verification.<ref>{{Cite news |last=Sparkes, Matthew |date=9 June 2014 |title=The coming digital anarchy |work=The Daily Telegraph |url=https://www.telegraph.co.uk/technology/news/10881213/The-coming-digital-anarchy.html |url-status=live |access-date=7 January 2015 |archive-url=https://web.archive.org/web/20150123190900/http://www.telegraph.co.uk/technology/news/10881213/The-coming-digital-anarchy.html |archive-date=23 January 2015}}</ref> A new block is created every 10 minutes on average, updating the blockchain across all nodes without central oversight. This process tracks bitcoin spending, ensuring each bitcoin is [[double-spending|spent only once]]. Unlike a traditional ledger that tracks physical currency, bitcoins exist digitally as [[unspent outputs of transactions]].<ref name="Antonopoulos2014" />{{rp|ch. 5}}
===2017 - 2018 ===
Bitcoin prices in 2017 were exceptionally volatile, starting at $998 and rising 1,245% to $13,412.44 on January 1, 2018.<ref name="Odata"/> On December 17 bitcoin's price reached an all time high of $19,666 and then fell 70% to $5,920 on February 6, 2018.<ref name= "MktWatch09022018"/>


===Addresses and transactions===
Throughout the rest of the first half of 2018, bitcoin's price fluctuated between $11,480 and $5,848. On July 1, 2018 bitcoin's price was $6,469.<ref name="BTUSDprice">{{cite web |title=Bitcoin (USD) Price |url=https://www.coindesk.com/price/ |website=Coindesk |accessdate=4 July 2018}}</ref>
[[File:Bitcoin Transaction Visual.svg|thumb|Simplified chain of ownership. In practice, a transaction can have more than one input and more than one output.<ref name="EconOfBTC" />]]
In the blockchain, bitcoins are linked to specific addresses that are hashes of a [[public key]]. Creating an address involves generating a random [[private key]] and then computing the corresponding address. This process is almost instant, but the reverse (finding the private key for a given address) is nearly impossible.<ref name="Antonopoulos2014" />{{rp|ch. 4}} Publishing a bitcoin address does not risk its private key, and it is extremely unlikely to accidentally generate a used key with funds. To use bitcoins, owners need their private key to [[digital signature|digitally sign]] transactions, which are verified by the network using the public key, keeping the private key secret.<ref name="Antonopoulos2014" />{{rp|ch. 5}}


Bitcoin transactions use a [[Forth (programming language)|Forth]]-like [[scripting language]],{{r|Antonopoulos2014|p=ch. 5}} involving one or more inputs and outputs. When sending bitcoins, a user specifies the recipients' addresses and the amount for each output. This allows sending bitcoins to several recipients in a single transaction. To prevent double-spending, each input must refer to a previous unspent output in the blockchain.<ref name="EconOfBTC">{{Cite conference |last1=Kroll |first1=Joshua A. |last2=Davey |first2=Ian C. |last3=Felten |first3=E. |title=The Economics of Bitcoin Mining, or Bitcoin in the Presence of Adversaries |conference=The Twelfth Workshop on the Economics of Information Security (WEIS 2013) |location=Washington, DC|date= 11–12 June 2013|s2cid=2794725 }}</ref> Using multiple inputs is similar to using multiple coins in a cash transaction. As in a cash transaction, the sum of inputs can exceed the intended sum of payments. In such a case, an additional output can return the change back to the payer.<ref name="EconOfBTC" /> Unallocated input satoshis in the transaction become the transaction fee.<ref name="EconOfBTC" />
=== Forks ===
{{see also|Fork (blockchain)|List of bitcoin forks}}
On 1 August 2017, a [[Fork (blockchain)#Hard fork|hard fork]] of bitcoin was created, known as [[Bitcoin Cash]].<ref>{{cite news|last1=Smith|first1=Jake|title=The Bitcoin Cash Hard Fork Will Show Us Which Coin Is Best|url=http://fortune.com/2017/08/11/bitcoin-cash-hard-fork-price-date-why/|accessdate=11 March 2018|work=Forbes|date=11 August 2017}}</ref> Bitcoin Cash has a larger block size limit and had an identical blockchain at the time of fork. On 24 October 2017 another hard fork, [[Bitcoin Gold]], was created. Bitcoin Gold changes the proof-of-work algorithm used in mining.<ref>{{cite web|title=Bitcoin Gold, the latest Bitcoin fork, explained|url=https://arstechnica.com/tech-policy/2017/11/bitcoin-gold-the-latest-bitcoin-fork-explained/|website=Ars Technica|accessdate=29 December 2017|deadurl=no|archiveurl=https://web.archive.org/web/20171229172206/https://arstechnica.com/tech-policy/2017/11/bitcoin-gold-the-latest-bitcoin-fork-explained/|archivedate=29 December 2017}}</ref>


Losing a private key means losing access to the bitcoins, with no other proof of ownership accepted by the [[bitcoin protocol|protocol]].<ref name=JEP/> For instance, in 2013, a user lost ₿7,500, valued at US$7.5 million, by accidentally discarding a [[Hard disk drive|hard drive]] with the private key.<ref>{{Cite news |date=29 November 2013 |title=Man Throws Away 7,500 Bitcoins, Now Worth $7.5 Million |work=CBS DC |url=http://washington.cbslocal.com/2013/11/29/man-throws-away-7500-bitcoins-now-worth-7-5-million/ |url-status=live |access-date=23 January 2014 |archive-url=https://web.archive.org/web/20140115062630/http://washington.cbslocal.com/2013/11/29/man-throws-away-7500-bitcoins-now-worth-7-5-million/ |archive-date=15 January 2014}}</ref> It is estimated that around 20% of all bitcoins are lost.<ref>{{Cite news |last=Krause |first=Elliott |date=5 July 2018 |title=A Fifth of All Bitcoin Is Missing. These Crypto Hunters Can Help |work=The Wall Street Journal |url=https://www.wsj.com/articles/a-fifth-of-all-bitcoin-is-missing-these-crypto-hunters-can-help-1530798731 |url-status=live |access-date=8 July 2018 |archive-url=https://web.archive.org/web/20180709010939/https://www.wsj.com/articles/a-fifth-of-all-bitcoin-is-missing-these-crypto-hunters-can-help-1530798731 |archive-date=9 July 2018}}</ref> The private key must also be kept secret as its exposure, such as through a [[data breach]], can lead to theft of the associated bitcoins.<ref name="Antonopoulos2014" />{{rp|ch. 10}}<ref>{{Cite news |last=Jeffries |first=Adrianne |date=19 December 2013 |title=How to steal Bitcoin in three easy steps |work=The Verge |url=https://www.theverge.com/2013/12/19/5183356/how-to-steal-bitcoin-in-three-easy-steps |url-status=live |access-date=17 January 2014 |archive-url=https://web.archive.org/web/20190727141228/https://www.theverge.com/2013/12/19/5183356/how-to-steal-bitcoin-in-three-easy-steps |archive-date=27 July 2019}}</ref> {{As of|2017|12}}, approximately ₿980,000 had been stolen from [[cryptocurrency exchange]]s.<ref>{{Cite news |last1=Harney |first1=Alexandra |last2=Stecklow |first2=Steve |date=16 November 2017 |title=Twice burned – How Mt. Gox's bitcoin customers could lose again |work=Reuters |url=https://www.reuters.com/investigates/special-report/bitcoin-gox/ |url-status=live |access-date=6 September 2018 |archive-url=https://web.archive.org/web/20190829052101/https://www.reuters.com/investigates/special-report/bitcoin-gox/ |archive-date=29 August 2019}}</ref>
==== Scaling Debates ====
As disagreements around scaling bitcoin heated up, several hard forks were proposed. [[Bitcoin XT]] was one proposal that aimed for 24 transactions per second. In order to accomplish this, it proposed increasing the block size from 1 megabyte to 8 megabytes. When Bitcoin XT was declined, some community members still wanted block sizes to increase. In response, a group of developers launched [[Bitcoin Classic]], which intended to increase the block size to only 2 megabytes. [[Bitcoin Unlimited]] set itself apart by allowing miners to decide on the size of their blocks, with nodes and miners limiting the size of blocks they accept, up to 16 megabytes.


==== Segwit Soft-fork ====
===Mining===
{{See also|Bitcoin protocol#Mining}}
[[Bitcoin Core]] developer Peter Wuille presented the idea of Segregated Witness ([[SegWit]]) in late 2015. Put simply, SegWit is a backward-compatible soft-fork that aims to reduce the size of each bitcoin transaction, thereby allowing more transactions to take place at once. Segwit activated on 1 August 2017.{{citation needed|date=June 2018}}
[[File:Argo Blockchain Mirabel Facility.jpg|thumb|Bitcoin mining [[Data center|facility]] with large amounts of mining hardware]]
The mining process in Bitcoin involves maintaining the blockchain through computer [[processing power]]. Miners group and broadcast new transactions into blocks, which are then verified by the network.<ref name="econbc">{{Cite news |date=31 October 2015 |title=The great chain of being sure about things |newspaper=The Economist |url=https://www.economist.com/briefing/2015/10/31/the-great-chain-of-being-sure-about-things |access-date=22 November 2023 |archive-date=4 December 2023 |archive-url=https://web.archive.org/web/20231204154941/https://www.economist.com/briefing/2015/10/31/the-great-chain-of-being-sure-about-things |url-status=live }}</ref> Each block must contain a proof of work (PoW) to be accepted,<ref name="econbc" /> involving finding a [[cryptographic nonce|nonce]] number that, combined with the block content, produces a [[cryptographic hash|hash]] numerically smaller than the network's ''difficulty target''.<ref name="Antonopoulos2014" />{{rp|ch. 8}} This PoW is simple to verify but hard to generate, requiring many attempts.<ref name="Antonopoulos2014" />{{rp|ch. 8}} PoW forms the basis of Bitcoin's [[Consensus (computer science)|consensus mechanism]].<ref name=Mingxiao2017>{{Cite conference |last1=Mingxiao |first1=Du |last2=Xiaofeng |first2=Ma |last3=Zhe |first3=Zhang |last4=Xiangwei |first4=Wang |last5=Qijun |first5=Chen |date=5–8 October 2017 |title=A review on consensus algorithm of blockchain |url=https://ieeexplore.ieee.org/document/8123011 |publisher=IEEE |pages=2567–2572 |doi=10.1109/SMC.2017.8123011 |isbn=978-1-5386-1645-1 |conference=2017 IEEE International Conference on Systems, Man, and Cybernetics (SMC) |location=Banff, AB, Canada |access-date=29 November 2023 |archive-date=24 November 2023 |archive-url=https://web.archive.org/web/20231124215821/http://ieeexplore.ieee.org/document/8123011 |url-status=live }}</ref>


The difficulty of generating a block is [[Deterministic algorithm|deterministically adjusted]] based on the [[Hashrate|mining power on the network]] by changing the difficulty target, which is recalibrated every 2,016 blocks (approximately two weeks) to maintain an average time of ten minutes between new blocks. The process requires significant computational power and specialized [[Computer hardware|hardware]].<ref name="Antonopoulos2014" />{{rp|ch. 8}}<ref>{{cite news |date=4 January 2014 |url=http://www.taipeitimes.com/News/biz/archives/2014/01/04/2003580449 |title=Bitcoin boom benefiting TSMC: report |newspaper=[[Taipei Times]] |access-date=22 October 2021 |archive-date=29 January 2023 |archive-url=https://web.archive.org/web/20230129102127/https://www.taipeitimes.com/News/biz/archives/2014/01/04/2003580449 |url-status=live }}</ref>
In response to SegWit, some developers and users decided to initiate a hard fork in order to avoid the protocol updates it brought about. [[Bitcoin Cash]] was the result, which increased the block size to 8 megabytes.<ref>{{cite news|url=http://fortune.com/2017/08/11/bitcoin-cash-hard-fork-price-date-why/|title=The Bitcoin Cash Hard Fork Will Show Us Which Coin Is Best|last1=Smith|first1=Jake|date=11 August 2017|work=Forbes|accessdate=11 March 2018}}</ref> There was another proposed hard fork called [[SegWit2x|Segwit2x]], which would have increased the block size to 2 megabytes. After a number of companies and individuals in the community decided to back out of the hard fork, the team behind SegWit2x cancelled their planned hard fork in November 2017.


Miners who successfully find a new block can collect transaction fees from the included transactions and a set reward in bitcoins.<ref name="bloombergvance111413">{{Cite magazine |last=Ashlee |first= Vance |author-link=Ashlee Vance |date=14 November 2013 |title=2014 Outlook: Bitcoin Mining Chips, a High-Tech Arms Race |url=http://www.businessweek.com/articles/2013-11-14/2014-outlook-bitcoin-mining-chips-a-high-tech-arms-race |url-status=dead |magazine=[[BusinessWeek]] |archive-url=https://web.archive.org/web/20131121225123/http://www.businessweek.com/articles/2013-11-14/2014-outlook-bitcoin-mining-chips-a-high-tech-arms-race |archive-date=21 November 2013 |access-date=24 November 2013}}</ref> To claim this reward, a special transaction called a ''coinbase'' is included in the block, with the miner as the payee. All bitcoins in existence have been created through this type of transaction.<ref name="Antonopoulos2014" />{{rp|ch. 8}} This reward is halved every 210,000 blocks until ₿21&nbsp;million,{{efn|name=supply|The exact number is ₿20,999,999.9769.{{r|Antonopoulos2014|page=ch. 8}}}} with new bitcoin issuance slated to end around 2140. Afterward, miners will only earn from transaction fees. These fees are determined by the transaction's size and the amount of data stored, measured in satoshis per byte.<ref>{{cite news |first1=Ritchie S. |last1=King |first2=Sam |last2=Williams |first3=David |last3=Yanofsky |date=17 December 2013 |title=By reading this article, you're mining bitcoins |url=http://qz.com/154877/by-reading-this-page-you-are-mining-bitcoins |work=[[Quartz (publication)|Quartz]] |access-date=17 December 2013 |archive-date=17 December 2013 |archive-url=https://web.archive.org/web/20131217221429/http://qz.com/154877/by-reading-this-page-you-are-mining-bitcoins/ |url-status=live }}</ref><ref name="EconOfBTC" /><ref name="Antonopoulos2014" />{{rp|ch. 8}}
==== New Features ====
Bitcoin Gold was a hard fork that followed several months later in October 2017 that changed the proof-of-work algorithm with the aim of restoring mining functionality to basic graphics processing units (GPU), as the developers felt that mining had become too specialized.<ref>{{cite web|url=https://arstechnica.com/tech-policy/2017/11/bitcoin-gold-the-latest-bitcoin-fork-explained/|title=Bitcoin Gold, the latest Bitcoin fork, explained|website=Ars Technica|archiveurl=https://web.archive.org/web/20171229172206/https://arstechnica.com/tech-policy/2017/11/bitcoin-gold-the-latest-bitcoin-fork-explained/|archivedate=29 December 2017|deadurl=no|accessdate=29 December 2017}}</ref> [[Bitcoin Private]], launched in March 2018, added the ability to keep certain details private in a transaction, in contrast to bitcoin which has a transparent transaction history.{{citation needed|date=June 2018}}


The proof of work system and the chaining of blocks make blockchain modifications very difficult, as altering one block requires changing all subsequent blocks. As more blocks are added, modifying older blocks becomes increasingly challenging.<ref>{{Cite news |last=Hampton |first=Nikolai |date=5 September 2016 |title=Understanding the blockchain hype: Why much of it is nothing more than snake oil and spin |work=[[Computerworld]] |url=http://www.computerworld.com.au/article/606253/understanding-blockchain-hype-why-much-it-nothing-more-than-snake-oil-spin/ |url-status=live |access-date=5 September 2016 |archive-url=https://web.archive.org/web/20160906171838/http://www.computerworld.com.au/article/606253/understanding-blockchain-hype-why-much-it-nothing-more-than-snake-oil-spin/ |archive-date=6 September 2016}}</ref><ref name="econbc" /> In case of disagreement, nodes trust the longest chain, which required the greatest amount of effort to produce.<ref name=Mingxiao2017/> To tamper or censor the ledger, one needs to control the majority of the global [[hashrate]].<ref name=Mingxiao2017/> The high cost required to reach this level of computational power guarantees the [[Computer security|security]] of the bitcoin blockchain.<ref name=Mingxiao2017/>
== Design ==


[[Environmental effects of bitcoin|Bitcoin mining's environmental impact]] is controversial and has attracted the attention of regulators, [[Legality of cryptocurrency by country or territory|leading to restrictions or incentives in various jurisdictions]].<ref name=Stoll2023>{{Cite report |url=https://www.jstor.org/stable/resrep51839 |title=Climate Impacts of Bitcoin Mining in the U.S. |last1=Stoll |first1=Christian |last2=Klaaßen |first2=Lena |date=June 2023 |publisher=MIT Center for Energy and Environmental Policy Research |last3=Gallersdörfer |first3=Ulrich |last4=Neumüller |first4=Alexander |series=Working Paper Series |access-date=24 November 2023 |archive-date=18 November 2023 |archive-url=https://web.archive.org/web/20231118132421/https://www.jstor.org/stable/resrep51839 |url-status=live }}</ref> {{As of|2022}}, a [[non-peer-reviewed]] study by the [[Cambridge Centre for Alternative Finance]] (CCAF) estimated that bitcoin mining represented {{sigfig|0.38|1}}% of [[World energy supply and consumption|global electricity consumption]].<ref name=Messina2023>{{Cite web |last=Messina |first=Irene |date=31 August 2023 |title=Bitcoin electricity consumption: an improved assessment |url=https://www.jbs.cam.ac.uk/2023/bitcoin-electricity-consumption |access-date=7 September 2023 |website=[[Cambridge Judge Business School]] |language=en-GB |archive-date=7 September 2023 |archive-url=https://web.archive.org/web/20230907181818/https://www.jbs.cam.ac.uk/2023/bitcoin-electricity-consumption/ |url-status=live }}</ref> Another 2022 non-peer-reviewed commentary published in ''[[Joule (journal)|Joule]]'' estimated that bitcoin mining was responsible for {{sigfig|0.19|1}}% of world greenhouse gas emissions.<ref name= deVries2022>{{Cite journal |last1=de Vries |first1=Alex |last2=Gallersdörfer |first2=Ulrich |last3=Klaaßen |first3=Lena |last4=Stoll |first4=Christian |date=16 March 2022 |title=Revisiting Bitcoin's carbon footprint |journal=[[Joule (journal)|Joule]] |volume=6 |issue=3 |page=499 |doi=10.1016/j.joule.2022.02.005 |s2cid=247143939 |issn=2542-4351|doi-access=free }}</ref> About half of the electricity used is generated through [[fossil fuel]]s.<ref name=NYT20220116>{{Cite news |last1=Huang |first1=Jon |last2=O'Neill |first2=Claire |last3=Tabuchi |first3=Hiroko |date=3 September 2021 |title=Bitcoin Uses More Electricity Than Many Countries. How Is That Possible? |work=[[The New York Times]] |url=https://www.nytimes.com/interactive/2021/09/03/climate/bitcoin-carbon-footprint-electricity.html |issn=0362-4331 |access-date=16 January 2022 |archive-date=17 February 2023 |archive-url=https://web.archive.org/web/20230217105559/https://www.nytimes.com/interactive/2021/09/03/climate/bitcoin-carbon-footprint-electricity.html |url-status=live }}</ref> Moreover, mining hardware's short lifespan results in [[electronic waste]].<ref name=deVries2021/> The amount of electrical energy consumed, and the e-waste generated, is comparable to that of Greece and the Netherlands, respectively.<ref name=deVries2021>{{Cite journal |last1=de Vries |first1=Alex |last2=Stoll |first2=Christian |date=December 2021 |title=Bitcoin's growing e-waste problem |url=https://www.sciencedirect.com/science/article/pii/S0921344921005103 |journal=Resources, Conservation and Recycling |volume=175 |page=105901 |doi=10.1016/j.resconrec.2021.105901 |s2cid=240585651 |issn=0921-3449 |access-date=24 November 2023 |archive-date=23 November 2021 |archive-url=https://web.archive.org/web/20211123145025/https://www.sciencedirect.com/science/article/abs/pii/S0921344921005103 |url-status=live }}</ref><ref name= deVries2022/>
=== Blockchain ===
{{broader|Blockchain}}


===Privacy and fungibility===
[[File:Utxo-count.svg|thumb|Number of [[unspent transaction outputs]]]]
Bitcoin is [[pseudonym]]ous, with funds linked to addresses, not real-world identities. While the owners of these addresses are not directly identified, all transactions are public on the blockchain. Patterns of use, like spending coins from multiple inputs, can hint at a common owner. Public data can sometimes be matched with known address owners.<ref>{{cite news |last=Simonite |first=Tom |date=5 September 2013 |title=Mapping the Bitcoin Economy Could Reveal Users' Identities |url=https://www.technologyreview.com/2013/09/05/176558/mapping-the-bitcoin-economy-could-reveal-users-identities/ |access-date=2 April 2014 |work=[[MIT Technology Review]] |archive-date=27 September 2020 |archive-url=https://web.archive.org/web/20200927062235/https://www.technologyreview.com/2013/09/05/176558/mapping-the-bitcoin-economy-could-reveal-users-identities/ |url-status=live }}</ref> [[List of bitcoin companies|Bitcoin exchanges]] might also need to collect personal data as per legal requirements.<ref>{{Cite news |last=Lee, Timothy |date=21 August 2013 |title=Five surprising facts about Bitcoin |newspaper=The Washington Post |url=https://www.washingtonpost.com/news/the-switch/wp/2013/08/21/five-surprising-facts-about-bitcoin-2 |access-date=21 November 2023 |archive-date=9 July 2022 |archive-url=https://web.archive.org/web/20220709135222/https://www.washingtonpost.com/news/the-switch/wp/2013/08/21/five-surprising-facts-about-bitcoin-2/ |url-status=live }}</ref> For enhanced [[Privacy and blockchain|privacy]], users can generate a new address for each transaction.<ref>{{Cite magazine |last=McMillan, Robert |date=6 June 2013 |title=How Bitcoin lets you spy on careless companies |url=https://www.wired.com/2013/06/bitcoin-retai/ |url-status=live |archive-url=https://web.archive.org/web/20140209202222/http://www.wired.co.uk/news/archive/2013-06/06/bitcoin-retail |archive-date=9 February 2014 |access-date=3 April 2020 |magazine=[[Wired UK]] }}</ref>


In the Bitcoin network, each bitcoin is treated equally, ensuring basic [[fungibility]]. However, users and applications can choose to differentiate between bitcoins. While wallets and software treat all bitcoins the same, each bitcoin's transaction history is recorded on the blockchain. This public record allows for [[Blockchain analysis|chain analysis]], where users can identify and potentially reject bitcoins from controversial sources.<ref>{{Cite book |last1=Anderson |first1=Ross |last2=Shumailov |first2=Ilia |last3=Ahmed |first3=Mansoor |title=Security Protocols XXVI |chapter=Making Bitcoin Legal |series=Lecture Notes in Computer Science |date=24 November 2018 |volume=11286 |chapter-url=https://www.research.ed.ac.uk/en/publications/making-bitcoin-legal |language=en |publisher=Springer |pages=243–253 |doi=10.1007/978-3-030-03251-7_29 |isbn=978-3-030-03250-0 |editor-last=Matyáš |editor-first=Vashek |editor2-last=Švenda |editor2-first=Petr |editor3-last=Stajano |editor3-first=Frank |editor4-last=Christianson |editor4-first=Bruce |access-date=24 November 2023 |archive-date=24 November 2023 |archive-url=https://web.archive.org/web/20231124165246/https://www.research.ed.ac.uk/en/publications/making-bitcoin-legal |url-status=live }}</ref> For example, in 2012, Mt. Gox froze accounts containing bitcoins identified as stolen.<ref>{{Cite conference |last1=Möser |first1=Malte |last2=Böhme |first2=Rainer |last3=Breuker |first3=Dominic |year=2013 |title=An Inquiry into Money Laundering Tools in the Bitcoin Ecosystem |url=https://maltemoeser.de/paper/money-laundering.pdf |conference=2013 APWG eCrime Researchers Summit |publisher=[[Institute of Electrical and Electronics Engineers|IEEE]] |isbn=978-1-4799-1158-5 |archive-url=https://web.archive.org/web/20180626110754/https://maltemoeser.de/paper/money-laundering.pdf |archive-date=26 June 2018 |access-date=19 June 2019 |url-status=live}}</ref>
The ''blockchain'' is a public [[ledger]] that records bitcoin transactions.{{r|econbc}} It is implemented as a chain of blocks, each block containing a hash of the previous block up to the ''genesis block''{{efn|The genesis block is the block number 0. The timestamp of the block is 2009-01-03 18:15:05. This block is unlike all other blocks in that it doesn't have a previous block to reference.}} of the chain. A novel solution accomplishes this without any trusted central authority: the maintenance of the blockchain is performed by a [[computer network|network]] of communicating [[node (networking)|nodes]] running bitcoin software.{{r|"primer"}} Transactions of the form ''payer X sends Y bitcoins to payee Z'' are [[Broadcasting (networking)|broadcast]] to this network using readily available software applications.


===Wallets===
Network nodes can validate transactions, add them to their copy of the ledger, and then broadcast these ledger additions to other nodes. The blockchain is a [[distributed database]] – to achieve independent verification of the chain of ownership of any and every bitcoin amount, each network node stores its own copy of the blockchain.<ref name="f_c2">{{cite news |url = https://www.telegraph.co.uk/technology/news/10881213/The-coming-digital-anarchy.html |title = The coming digital anarchy |publisher = Telegraph Media Group Limited |work = The Telegraph |date = 9 June 2014 |accessdate = 7 January 2015 |author = Sparkes, Matthew |location = London |deadurl = no |archiveurl = https://web.archive.org/web/20150123190900/http://www.telegraph.co.uk/technology/news/10881213/The-coming-digital-anarchy.html |archivedate = 23 January 2015 |df = dmy-all }}</ref> Approximately once every 10 minutes, a new group of accepted transactions, a block, is created, added to the blockchain, and quickly published to all nodes. This allows bitcoin software to determine when a particular bitcoin amount has been spent, which is necessary in order to prevent [[double-spending]] in an environment without central oversight. Whereas a conventional ledger records the transfers of actual [[Banknote|bills]] or [[promissory note]]s that exist apart from it, the blockchain is the only place that bitcoins can be said to exist in the form of [[unspent outputs of transactions]].<ref name="Antonopoulos2014"/>{{rp|ch. 5}}

=== Transactions ===
{{See also|Bitcoin network }}
[[File:BTC number of transactions per month.png|thumb|Number of bitcoin transactions per month (logarithmic scale)<ref name="Blockchain.info" />]]

Transactions are defined using a [[Forth (programming language)|Forth]]-like scripting language.{{r|Antonopoulos2014|p=ch. 5}} Transactions consist of one or more ''inputs'' and one or more ''outputs''. When a user sends bitcoins, the user designates each address and the amount of bitcoin being sent to that address in an output. To prevent double spending, each input must refer to a previous unspent output in the blockchain.<ref name="EconOfBTC">{{cite web |url = http://www.econinfosec.org/archive/weis2013/papers/KrollDaveyFeltenWEIS2013.pdf |title = The Economics of Bitcoin Mining, or Bitcoin in the Presence of Adversaries |work = The Twelfth Workshop on the Economics of Information Security (WEIS 2013) |date = 11–12 June 2013 |accessdate = 26 April 2016 |author1 = Joshua A. Kroll |author2 = Ian C. Davey |author3 = Edward W. Felten |quote = A transaction fee is like a tip or gratuity left for the miner. |deadurl = no |archiveurl = https://web.archive.org/web/20160509053819/http://www.econinfosec.org/archive/weis2013/papers/KrollDaveyFeltenWEIS2013.pdf |archivedate = 9 May 2016 |df = dmy-all }}</ref> The use of multiple inputs corresponds to the use of multiple coins in a cash transaction. Since transactions can have multiple outputs, users can send bitcoins to multiple recipients in one transaction. As in a cash transaction, the sum of inputs (coins used to pay) can exceed the intended sum of payments. In such a case, an additional output is used, returning the change back to the payer.<ref name="EconOfBTC" /> Any input satoshis not accounted for in the transaction outputs become the transaction fee.<ref name="EconOfBTC" />

=== Transaction fees ===

[[File:An actual Bitcoin transaction from the Kraken cryptocurrency exchange to a hardware LedgerWallet.jpg|thumb|An actual bitcoin transaction including the fee from a webbased [[cryptocurrency exchange]] to a hardware wallet.]]

Paying a transaction fee is optional.<ref name="EconOfBTC" /> Miners can choose which transactions to process,<ref name="EconOfBTC" /> and they are incentivised to prioritize those that pay higher fees.

Because the size of mined blocks is capped by the network, miners choose transactions based on the fee paid relative to their storage size, not the absolute amount of money paid as a fee. Thus, fees are generally measured in ''satoshis per byte'', or ''sat/b''. The size of transactions is dependent on the number of inputs used to create the transaction, and the number of outputs.<ref name="Antonopoulos2014" />{{rp|ch. 8}}

=== Ownership ===

[[File:Bitcoin Transaction Visual.svg|thumb|Simplified chain of ownership.<ref name="paper" /> In reality, a transaction can have more than one input and more than one output.]]

In the blockchain, bitcoins are registered to bitcoin addresses. Creating a bitcoin address is nothing more than picking a random valid private key and computing the corresponding bitcoin address. This computation can be done in a split second. But the reverse (computing the private key of a given bitcoin address) is mathematically unfeasible and so users can tell others and make public a bitcoin address without compromising its corresponding private key. Moreover, the number of valid private keys is so vast that it is extremely unlikely someone will compute a key-pair that is already in use and has funds. The vast number of valid private keys makes it unfeasible that brute force could be used for that. To be able to spend the bitcoins, the owner must know the corresponding [[private key]] and [[digital signature|digitally sign]] the transaction. The network verifies the signature using the [[public key]].<ref name="Antonopoulos2014" />{{rp|ch. 5}}

If the private key is lost, the [[bitcoin network]] will not recognize any other evidence of ownership;<ref name="primer" /> the coins are then unusable, and effectively lost. For example, in 2013 one user claimed to have lost 7,500 bitcoins, worth $7.5 million at the time, when he accidentally discarded a hard drive containing his private key.<ref>{{cite news |title = Man Throws Away 7,500 Bitcoins, Now Worth $7.5 Million |date = 29 November 2013 |url = http://washington.cbslocal.com/2013/11/29/man-throws-away-7500-bitcoins-now-worth-7-5-million/ |work = CBS DC |accessdate = 23 January 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20140115062630/http://washington.cbslocal.com/2013/11/29/man-throws-away-7500-bitcoins-now-worth-7-5-million/ |archivedate = 15 January 2014 |df = dmy-all }}</ref> A backup of his key(s) would have prevented this.

=== Mining ===
[[File:USB Erupter.jpg|thumb|Amateur bitcoin mining with a small ASIC. This was when difficulty was much lower, and is no longer feasible.]]

[[File:History of Bitcoin difficulty.svg|thumb|[[Semi-log plot]] of relative mining difficulty{{efn|Relative mining difficulty is defined as the ratio of the difficulty target on 9 January 2009 to the current difficulty target.}}<ref name="Blockchain.info">{{cite web |url = https://blockchain.info/charts |title = Charts |accessdate = 2 November 2014 |publisher = [[Blockchain.info]] |deadurl = no |archiveurl = https://web.archive.org/web/20141103020741/http://blockchain.info/charts |archivedate = 3 November 2014 |df = dmy-all }}</ref>]]

''Mining'' is a record-keeping service done through the use of computer [[processing power]].{{efn|It is misleading to think that there is an analogy between gold mining and bitcoin mining. The fact is that gold miners are rewarded for producing gold, while bitcoin miners are not rewarded for producing bitcoins; they are rewarded for their record-keeping services.<ref name="Andolfatto2014-03">{{cite web |url = http://www.stlouisfed.org/dialogue-with-the-fed/assets/Bitcoin-3-31-14.pdf |title = Bitcoin and Beyond: The Possibilities and Pitfalls of Virtual Currencies |publisher = Federal Reserve Bank of St. Louis |work = Dialogue with the Fed |date = 31 March 2014 |accessdate = 16 April 2014 |author = Andolfatto, David |deadurl = no |archiveurl = https://web.archive.org/web/20140409044505/http://www.stlouisfed.org/dialogue-with-the-fed/assets/Bitcoin-3-31-14.pdf |archivedate = 9 April 2014 |df = dmy-all }}</ref>}} Miners keep the blockchain consistent, complete, and unalterable by repeatedly grouping newly broadcast transactions into a ''block'', which is then broadcast to the network and verified by recipient nodes.<ref name="econbc">{{cite news |title = The great chain of being sure about things |url = https://www.economist.com/news/briefing/21677228-technology-behind-bitcoin-lets-people-who-do-not-know-or-trust-each-other-build-dependable |accessdate = 3 July 2016 |work = The Economist |publisher = The Economist Newspaper Limited |date = 31 October 2015 |deadurl = no |archiveurl = https://web.archive.org/web/20160703000844/http://www.economist.com/news/briefing/21677228-technology-behind-bitcoin-lets-people-who-do-not-know-or-trust-each-other-build-dependable |archivedate = 3 July 2016 |df = dmy-all }}</ref> Each block contains a [[SHA-256]] [[cryptographic hash]] of the previous block,<ref name="econbc" /> thus linking it to the previous block and giving the blockchain its name.<ref name="Antonopoulos2014" />{{rp|ch. 7}}<ref name="econbc" />

To be accepted by the rest of the network, a new block must contain a so-called ''[[Proof-of-work system#Bitcoin-type proof-of-work|proof-of-work]]'' (PoW).<ref name="econbc" /> The system used is based on [[Adam Back]]'s 1997 anti-[[email spam|spam]] scheme, [[Hashcash]].<ref name="paper" /><ref>{{cite journal|last1=Blocki|first1=Jeremiah|last2=Zhou|first2=Hong-Sheng|title=Designing Proof of Human-Work Puzzles for Cryptocurrency and Beyond|journal=Theory of Cryptography|date=1 January 2016|volume=9986|pages=517–546|doi=10.1007/978-3-662-53644-5_20|url=https://link.springer.com/chapter/10.1007%2F978-3-662-53644-5_20|accessdate=4 February 2018|publisher=Springer Berlin Heidelberg|series=Lecture Notes in Computer Science|isbn=978-3-662-53643-8}}</ref> The PoW requires miners to find a number called a ''[[cryptographic nonce|nonce]]'', such that when the block content is [[cryptographic hash|hashed]] along with the nonce, the result is numerically smaller than the network's ''difficulty target''.<ref name="Antonopoulos2014" />{{rp|ch. 8}} This proof is easy for any node in the network to verify, but extremely time-consuming to generate, as for a secure cryptographic hash, miners must try many different nonce values (usually the sequence of tested values is the ascending natural numbers: 0, 1, 2, 3, ...<ref name="Antonopoulos2014" />{{rp|ch. 8}}) before meeting the difficulty target.

Every 2,016 blocks (approximately 14 days at roughly 10 min per block), the difficulty target is adjusted based on the network's recent performance, with the aim of keeping the average time between new blocks at ten minutes. In this way the system automatically adapts to the total amount of mining power on the network.<ref name="Antonopoulos2014" />{{rp|ch. 8}} Between 1 March 2014 and 1 March 2015, the average number of nonces miners had to try before creating a new block increased from 16.4 quintillion to 200.5 quintillion.<ref name="diffhistory">{{cite web |url = https://blockchain.info/charts/difficulty?timespan=all&showDataPoints=false&daysAverageString=1&show_header=true&scale=0&address= |title = Difficulty History |publisher = Blockchain.info |accessdate = 26 March 2015 |type = The ratio of all hashes over valid hashes is D x 4,295,032,833, where D is the published "Difficulty" figure. |deadurl = no |archiveurl = https://web.archive.org/web/20150408212548/https://blockchain.info/charts/difficulty?timespan=all&showDataPoints=false&daysAverageString=1&show_header=true&scale=0&address= |archivedate = 8 April 2015 |df = dmy-all }}</ref>

The proof-of-work system, alongside the chaining of blocks, makes modifications of the blockchain extremely hard, as an attacker must modify all subsequent blocks in order for the modifications of one block to be accepted.<ref>{{cite news |last1 = Hampton |first1 = Nikolai |title = Understanding the blockchain hype: Why much of it is nothing more than snake oil and spin |url = http://www.computerworld.com.au/article/606253/understanding-blockchain-hype-why-much-it-nothing-more-than-snake-oil-spin/ |accessdate = 5 September 2016 |work = Computerworld |publisher = IDG |date = 5 September 2016 |deadurl = no |archiveurl = https://web.archive.org/web/20160906171838/http://www.computerworld.com.au/article/606253/understanding-blockchain-hype-why-much-it-nothing-more-than-snake-oil-spin/ |archivedate = 6 September 2016 |df = dmy-all }}</ref> As new blocks are mined all the time, the difficulty of modifying a block increases as time passes and the number of subsequent blocks (also called ''confirmations'' of the given block) increases.<ref name="econbc" />

==== Pooled mining ====

{{Main|Mining pool}}
Computing power is often bundled together or "pooled" to reduce variance in miner income. Individual mining rigs often have to wait for long periods to confirm a block of transactions and receive payment. In a pool, all participating miners get paid every time a participating server solves a block. This payment depends on the amount of work an individual miner contributed to help find that block.<ref name=Techcrunch12>{{cite web|last=Biggs|first=John|title=How To Mine Bitcoins|url=https://techcrunch.com/2013/04/08/how-to-mine-bitcoins/|publisher=Techcrunch|date=8 April 2013|deadurl=no|archiveurl=https://web.archive.org/web/20170706132517/https://techcrunch.com/2013/04/08/how-to-mine-bitcoins/|archivedate=6 July 2017}}</ref>

=== Supply ===

[[File:Total-bitcoins.svg|thumb|Total bitcoins in circulation.<ref name="Blockchain.info" />]]

The successful miner finding the new block is rewarded with newly created bitcoins and transaction fees.<ref name="bloombergvance111413">{{cite web |url = http://www.businessweek.com/articles/2013-11-14/2014-outlook-bitcoin-mining-chips-a-high-tech-arms-race |title = 2014 Outlook: Bitcoin Mining Chips, a High-Tech Arms Race |publisher = Businessweek |date = 14 November 2013 |author = Ashlee Vance |accessdate = 24 November 2013 |deadurl = no |archiveurl = https://web.archive.org/web/20131121225123/http://www.businessweek.com/articles/2013-11-14/2014-outlook-bitcoin-mining-chips-a-high-tech-arms-race |archivedate = 21 November 2013 |df = dmy-all }}</ref> {{as of|2016|07|09}},<ref name="BlockChain.info">{{cite web |url = https://blockchain.info/block/000000000000000002cce816c0ab2c5c269cb081896b7dcb34b8422d6b74ffa1 |title = Block #420000 |publisher = Blockchain.info |accessdate = 11 September 2016 |deadurl = no |archiveurl = https://web.archive.org/web/20160918115932/https://blockchain.info/block/000000000000000002cce816c0ab2c5c269cb081896b7dcb34b8422d6b74ffa1 |archivedate = 18 September 2016 |df = dmy-all }}</ref> the reward amounted to 12.5 newly created bitcoins per block added to the blockchain. To claim the reward, a special transaction called a ''coinbase'' is included with the processed payments.<ref name="Antonopoulos2014" />{{rp|ch. 8}} All bitcoins in existence have been created in such coinbase transactions. The [[bitcoin protocol]] specifies that the reward for adding a block will be halved every 210,000 blocks (approximately every four years). Eventually, the reward will decrease to zero, and the limit of 21 million bitcoins{{efn|The exact number is 20,999,999.9769 bitcoins.{{r|Antonopoulos2014|page=ch. 8}}}} will be reached [[circa|c.]] 2140; the record keeping will then be rewarded by transaction fees solely.<ref name="KWY">{{cite web |url = http://qz.com/154877/by-reading-this-page-you-are-mining-bitcoins/ |title = By reading this article, you're mining bitcoins |publisher = Atlantic Media Co |work = qz.com |date = 17 December 2013 |accessdate = 17 December 2013 |author1 = Ritchie S. King |author2 = Sam Williams |author3 = David Yanofsky |deadurl = no |archiveurl = https://web.archive.org/web/20131217221429/http://qz.com/154877/by-reading-this-page-you-are-mining-bitcoins/ |archivedate = 17 December 2013 |df = dmy-all }}</ref>

In other words, bitcoin's inventor Nakamoto set a [[monetary policy]] based on [[artificial scarcity]] at bitcoin's inception that there would only ever be 21&nbsp;million bitcoins in total. Their numbers are being released roughly every ten minutes and the rate at which they are generated would drop by half every four years until all were in [[Circulation (currency)|circulation]].<ref>{{cite news |last1 = Shin |first1 = Laura |title = Bitcoin Production Will Drop By Half In July, How Will That Affect The Price? |url = https://www.forbes.com/sites/laurashin/2016/05/24/bitcoin-production-will-drop-by-half-in-july-how-will-that-affect-the-price/#79bdaa0999e1 |accessdate = 13 July 2016 |work = Forbes |date = 24 May 2016 |deadurl = no |archiveurl = https://web.archive.org/web/20160524141916/http://www.forbes.com/sites/laurashin/2016/05/24/bitcoin-production-will-drop-by-half-in-july-how-will-that-affect-the-price/#79bdaa0999e1 |archivedate = 24 May 2016 |df = dmy-all }}</ref>

=== Wallets ===
{{Broader|Cryptocurrency wallet}}
{{Broader|Cryptocurrency wallet}}
{{multiple image
| total_width = 600
| align = center
| image1 = Bitcoin-core-v0.10.0.png
| caption1 = Screenshot of [[Bitcoin Core]]
| image2 = Sample Bitcoin paper wallet.png
| caption2 = A paper wallet with the address as a [[QR code]] while the private key is hidden
| image3 = 10elqpi.jpg
| caption3 = A hardware wallet which processes bitcoin transactions without exposing private keys
}}
Bitcoin wallets were the first [[cryptocurrency wallet]]s, enabling users to store the information necessary to transact bitcoins.<ref>{{cite news |first1=Adam |last1=Serwer |first2=Dana|last2= Liebelson |date=10 April 2013 |title=Bitcoin, Explained |url=https://www.motherjones.com/politics/2013/04/what-is-bitcoin-explained |url-status=live |archive-url=https://web.archive.org/web/20140427022315/https://www.motherjones.com/politics/2013/04/what-is-bitcoin-explained |archive-date=27 April 2014 |access-date=26 April 2014 |work=[[Mother Jones (magazine)|Mother Jones]]}}</ref>{{r|Antonopoulos2014|p=ch. 1, glossary}} The first wallet program, simply named ''Bitcoin'', and sometimes referred to as the ''Satoshi client'', was released in 2009 by Nakamoto as [[open-source software]].<ref name="NY2011" /> [[Bitcoin Core]] is among the best known [[Client (computing)|clients]]. [[fork (software development)|Forks]] of Bitcoin Core exist such as [[Bitcoin Unlimited]].<ref>{{Cite news |last=Vigna |first=Paul |date=17 January 2016 |title=Is Bitcoin Breaking Up? |work=The Wall Street Journal |url=https://www.wsj.com/articles/is-bitcoin-breaking-up-1453044493 |url-status=live |access-date=8 November 2016 |archive-url=https://web.archive.org/web/20160820144312/http://www.wsj.com/articles/is-bitcoin-breaking-up-1453044493 |archive-date=20 August 2016}}</ref> Wallets can be full clients, with a full copy of the blockchain to check the validity of mined blocks,{{r|Antonopoulos2014|p=ch. 1}} or lightweight clients, just to send and receive transactions without a local copy of the entire blockchain.<ref>{{Cite book |last1=Gervais |first1=Arthur |last2=Capkun |first2=Srdjan |last3=Karame |first3=Ghassan O. |last4=Gruber |first4=Damian |title=Proceedings of the 30th Annual Computer Security Applications Conference |chapter=On the privacy provisions of Bloom filters in lightweight bitcoin clients |date=8 December 2014 |chapter-url=https://doi.org/10.1145/2664243.2664267 |series=ACSAC '14 |location=New York, NY, USA |publisher=Association for Computing Machinery |pages=326–335 |doi=10.1145/2664243.2664267 |isbn=978-1-4503-3005-3 |s2cid=9161497 |access-date=22 November 2023 |archive-date=21 April 2024 |archive-url=https://web.archive.org/web/20240421113526/https://consent.cookiebot.com/uc.js |url-status=live }}</ref> Third-party internet services called online wallets store users' credentials on their servers, making them susceptible of hacks.<ref>{{Cite news |first=Bill |last=Barhydt |date=4 June 2014 |title=3 reasons Wall Street can't stay away from bitcoin |publisher=CNBC |url=https://www.cnbc.com/2014/06/04/3-reasons-wall-street-cant-stay-away-from-bitcoin.html |access-date=22 November 2023 |archive-date=4 December 2023 |archive-url=https://web.archive.org/web/20231204140256/https://www.cnbc.com/2014/06/04/3-reasons-wall-street-cant-stay-away-from-bitcoin.html |url-status=live }}</ref> Cold storage protects bitcoins from such hacks by keeping private keys offline, either through specialized hardware wallets or paper printouts.<ref>{{Cite news |last=Roberts |first=Daniel |date=15 December 2017 |title=How to send bitcoin to a hardware wallet |work=Yahoo Finance |url=https://finance.yahoo.com/news/send-bitcoin-hardware-wallet-140141385.html |url-status=live |access-date=17 February 2018 |archive-url=https://web.archive.org/web/20180217142235/https://finance.yahoo.com/news/send-bitcoin-hardware-wallet-140141385.html |archive-date=17 February 2018}}</ref><ref name="Antonopoulos2014" />{{rp|ch. 4}}


=== Scalability and decentralization challenges ===
[[File:Screenshot of Bitcoin-qt-0.5.2.png|thumb|[[Bitcoin Core]] wallet GUI]]
Nakamoto limited the block size to one [[megabyte]].<ref>{{Cite news |last=Mike Orcutt |date=19 May 2015 |title=Leaderless Bitcoin Struggles to Make Its Most Crucial Decision |work=MIT Technology Review |url=https://www.technologyreview.com/s/537486/leaderless-bitcoin-struggles-to-make-its-most-crucial-decision/ |access-date=15 November 2016 |archive-date=18 October 2017 |archive-url=https://wayback.archive-it.org/all/20171018075515/https://www.technologyreview.com/s/537486/leaderless-bitcoin-struggles-to-make-its-most-crucial-decision/ |url-status=live }}</ref> The limited block size and frequency can lead to delayed processing of transactions, increased fees and a [[Bitcoin scalability problem]].<ref>{{Cite news |last=Orcutt |first=Mike |date=19 May 2015 |title=Leaderless Bitcoin Struggles to Make Its Most Crucial Decision |work=MIT Technology Review |url=https://www.technologyreview.com/s/537486/leaderless-bitcoin-struggles-to-make-its-most-crucial-decision/ |url-status=live |access-date=22 June 2017 |archive-url=https://wayback.archive-it.org/all/20171018075515/https://www.technologyreview.com/s/537486/leaderless-bitcoin-struggles-to-make-its-most-crucial-decision/ |archive-date=18 October 2017}}</ref> The [[Lightning Network]], [[Abstraction layer|second-layer]] [[routing]] network, is a potential scaling solution.<ref name="Antonopoulos2014"/>{{rp|ch. 8}}

[[File:Electrum Bitcoin Wallet.png|thumb|Electrum bitcoin wallet]]

A ''wallet'' stores the information necessary to transact bitcoins. While wallets are often described as a place to hold<ref>{{cite web |url = http://www.motherjones.com/politics/2013/04/what-is-bitcoin-explained |title = Bitcoin, Explained |publisher = Mother Jones |work = motherjones.com |date = 10 April 2013 |accessdate = 26 April 2014 |author1 = Adam Serwer |author2 = Dana Liebelson |lastauthoramp = yes |deadurl = no |archiveurl = https://web.archive.org/web/20140427022315/http://www.motherjones.com/politics/2013/04/what-is-bitcoin-explained |archivedate = 27 April 2014 |df = dmy-all }}</ref> or store bitcoins,<ref name=3ceos /> due to the nature of the system, bitcoins are inseparable from the blockchain transaction ledger. A better way to describe a wallet is something that "stores the digital credentials for your bitcoin holdings"<ref name=3ceos>{{cite news |url = https://www.forbes.com/sites/johnvillasenor/2014/04/26/secure-bitcoin-storage-a-qa-with-three-bitcoin-company-ceos/ |title = Secure Bitcoin Storage: A Q&A With Three Bitcoin Company CEOs |publisher = Forbes |work = forbes.com |date = 26 April 2014 |accessdate = 26 April 2014 |author = Villasenor, John |deadurl = no |archiveurl = https://web.archive.org/web/20140427011731/http://www.forbes.com/sites/johnvillasenor/2014/04/26/secure-bitcoin-storage-a-qa-with-three-bitcoin-company-ceos/ |archivedate = 27 April 2014 |df = dmy-all }}</ref> and allows one to access (and spend) them. Bitcoin uses [[public-key cryptography]], in which two cryptographic keys, one public and one private, are generated.<ref name="Economist113013Pressure">{{cite news |url = https://www.economist.com/news/technology-quarterly/21590766-virtual-currency-it-mathematically-elegant-increasingly-popular-and-highly |title = Bitcoin: Bitcoin under pressure |work = The Economist |date = 30 November 2013 |accessdate = 30 November 2013 |deadurl = no |archiveurl = https://web.archive.org/web/20131130032403/http://www.economist.com/news/technology-quarterly/21590766-virtual-currency-it-mathematically-elegant-increasingly-popular-and-highly |archivedate = 30 November 2013 |df = dmy-all }}</ref> At its most basic, a wallet is a collection of these keys.

There are three modes which wallets can operate in. They have an inverse relationship with regards to trustlessness and computational requirements.
* ''Full clients'' verify transactions directly by downloading a full copy of the blockchain (over 150&nbsp;GB {{as of|2018|January}}).<ref>{{cite web|title=Blockchain Size|url=https://blockchain.info/charts/blocks-size|website=Blockchain.info|accessdate=16 January 2018|deadurl=no|archiveurl=https://web.archive.org/web/20170527050820/https://blockchain.info/charts/blocks-size|archivedate=27 May 2017}}</ref> They are the most secure and reliable way of using the network, as trust in external parties is not required. Full clients check the validity of mined blocks, preventing them from transacting on a chain that breaks or alters network rules.<ref>{{cite web |last1 = Torpey |first1 = Kyle |title = You Really Should Run a Bitcoin Full Node: Here's Why |url = https://bitcoinmagazine.com/articles/you-really-should-run-full-bitcoin-node-heres-why/ |website = Bitcoin Magazine |accessdate = 29 November 2017 |deadurl = no |archiveurl = https://web.archive.org/web/20170703210734/https://bitcoinmagazine.com/articles/you-really-should-run-full-bitcoin-node-heres-why/ |archivedate = 3 July 2017 |df = dmy-all }}</ref> Because of its size and complexity, downloading and verifying the entire blockchain is not suitable for all computing devices.
* ''Lightweight clients'' consult full clients to send and receive transactions without requiring a local copy of the entire blockchain (see [[Bitcoin network#Payment verification|simplified payment verification]] – SPV). This makes lightweight clients much faster to set up and allows them to be used on low-power, low-bandwidth devices such as smartphones. When using a lightweight wallet, however, the user must trust the server to a certain degree, as it can report faulty values back to the user. Lightweight clients follow the longest blockchain and do not ensure it is valid, requiring trust in miners.<ref name="LBC">{{cite web |last1 = Gervais |first1 = Arthur |last2 = O. Karame |first2 = Ghassan |last3 = Gruber |first3 = Damian |last4 = Capkun |first4 = Srdjan |title = On the Privacy Provisions of Bloom Filters in Lightweight Bitcoin Clients |url = https://eprint.iacr.org/2014/763.pdf |accessdate = 3 September 2016 |deadurl = no |archiveurl = https://web.archive.org/web/20161005045518/https://eprint.iacr.org/2014/763.pdf |archivedate = 5 October 2016 |df = dmy-all }}</ref>

Third-party internet services called ''online wallets'' offer similar functionality but may be easier to use. In this case, credentials to access funds are stored with the online wallet provider rather than on the user's hardware.<ref>{{cite news |title = Be Your Own Bank: Bitcoin Wallet for Apple |url = https://www.forbes.com/sites/jonmatonis/2012/04/26/be-your-own-bank-bitcoin-wallet-for-apple/ |author = Jon Matonis |date = 26 April 2012 |accessdate = 17 November 2014 |publisher = Forbes |deadurl = no |archiveurl = https://web.archive.org/web/20141012002316/http://www.forbes.com/sites/jonmatonis/2012/04/26/be-your-own-bank-bitcoin-wallet-for-apple/ |archivedate = 12 October 2014 |df = dmy-all }}</ref><ref>{{cite news |author1 = Bill Barhydt |title = 3 reasons Wall Street can't stay away from bitcoin |url = https://www.cnbc.com/id/101711220 |accessdate = 2 April 2015 |publisher = NBCUniversal |date = 4 June 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20150403052101/http://www.cnbc.com/id/101711220 |archivedate = 3 April 2015 |df = dmy-all }}</ref> As a result, the user must have complete trust in the wallet provider. A malicious provider or a breach in server security may cause entrusted bitcoins to be stolen. An example of such a security breach occurred with [[Mt. Gox]] in 2011.<ref name="mtgoxdetails">{{cite web |url = https://www.bbc.com/news/technology-26420932 |title = MtGox gives bankruptcy details |publisher = BBC |work = bbc.com |date = 4 March 2014 |accessdate = 13 March 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20140312001338/http://www.bbc.com/news/technology-26420932 |archivedate = 12 March 2014 }}</ref> This has led to the often-repeated meme "Not your keys, not your bitcoin".<ref>{{cite web|title=Antonopoulos: Your Keys, Your Bitcoin. Not Your Keys, Not Your Bitcoin|url=https://cointelegraph.com/news/antonopoulos-your-keys-your-bitcoin-not-your-keys-not-your-bitcoin|website=Cointelegraph|accessdate=16 February 2018}}</ref>

[[File:Bitcoin paper wallet generated at bitaddress.jpg|thumb|Bitcoin paper wallet]]

[[File:10elqpi.jpg|thumb|Trezor hardware wallet]]

''Physical wallets'' store offline the credentials necessary to spend bitcoins.<ref name=3ceos /> One notable example was a novelty coin with these credentials printed on the reverse side.<ref name="theverge">{{cite web |last = Staff |first = Verge |url = https://www.theverge.com/2013/12/13/5207256/casascius-maker-of-shiny-physical-bitcoins-shut-down-by-treasury |title = Casascius, maker of shiny physical bitcoins, shut down by Treasury Department |publisher = The Verge |date = 13 December 2013 |accessdate = 10 January 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20140110010445/http://www.theverge.com/2013/12/13/5207256/casascius-maker-of-shiny-physical-bitcoins-shut-down-by-treasury |archivedate = 10 January 2014 |df = dmy-all }}</ref> ''Paper wallets'' are simply paper printouts.

Another type of wallet called a ''hardware wallet'' keeps credentials offline while facilitating transactions.<ref>{{cite news|last1=Roberts|first1=Daniel|title=How to send bitcoin to a hardware wallet|url=https://finance.yahoo.com/news/send-bitcoin-hardware-wallet-140141385.html|accessdate=17 February 2018|work=Yahoo Finance|date=15 December 2017}}</ref>

=== Implementations ===
{{further|Bitcoin Core}}
The first wallet program – simply named "Bitcoin" – was released in 2009 by [[Satoshi Nakamoto]] as [[open source|open-source]] code.<ref name="NY2011" /> In version 0.5 the client moved from the [[wxWidgets]] user interface toolkit to [[Qt (software)|Qt]], and the whole bundle was referred to as "Bitcoin-Qt".<ref name="Bitcoin Clients">{{Cite thesis |url = http://publications.theseus.fi/bitstream/handle/10024/47166/Skudnov_Rostislav.pdf?sequence=1 |first = Rostislav |last = Skudnov |title = Bitcoin Clients |type = Bachelor's Thesis |year = 2012 |publisher = [[Turku University of Applied Sciences]] |accessdate = 16 January 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20140118104507/http://publications.theseus.fi/bitstream/handle/10024/47166/Skudnov_Rostislav.pdf?sequence=1 |archivedate = 18 January 2014 |df = dmy-all }}</ref> After the release of version 0.9, the software bundle was renamed "Bitcoin Core" to distinguish itself from the underlying network.<ref>{{cite web |title = Bitcoin Core version 0.9.0 released |url = https://bitcoin.org/en/release/v0.9.0 |website = bitcoin.org |accessdate = 8 January 2015 |deadurl = no |archiveurl = https://web.archive.org/web/20150227213613/https://bitcoin.org/en/release/v0.9.0 |archivedate = 27 February 2015 |df = dmy-all }}</ref><ref>{{cite news |last1 = Metz |first1 = Cade |title = The Bitcoin Schism Shows the Genius of Open Source |url = https://www.wired.com/2015/08/bitcoin-schism-shows-genius-open-source/ |accessdate = 3 July 2016 |work = Wired |publisher = Condé Nast |date = 19 August 2015 |deadurl = no |archiveurl = https://web.archive.org/web/20160630230101/http://www.wired.com/2015/08/bitcoin-schism-shows-genius-open-source |archivedate = 30 June 2016 |df = dmy-all }}</ref> It is sometimes referred to as the "Satoshi client".

Bitcoin Core is, perhaps, the best known implementation or client. Alternative clients ([[fork (software development)|forks]] of Bitcoin Core) exist, such as [[Bitcoin XT]], [[Bitcoin Unlimited]],<ref name="breakingup">{{cite news |last1 = Vigna |first1 = Paul |title = Is Bitcoin Breaking Up? |url = https://www.wsj.com/articles/is-bitcoin-breaking-up-1453044493 |accessdate = 8 November 2016 |work = The Wall Street Journal |date = 17 January 2016 |deadurl = no |archiveurl = https://web.archive.org/web/20160820144312/http://www.wsj.com/articles/is-bitcoin-breaking-up-1453044493 |archivedate = 20 August 2016 |df = dmy-all }}</ref> and Parity Bitcoin.<ref>{{cite news |last1 = Allison |first1 = Ian |title = Ethereum co-founder Dr Gavin Wood and company release Parity Bitcoin |url = http://www.ibtimes.co.uk/ethereum-co-founder-dr-gavin-wood-company-release-parity-bitcoin-1619025 |accessdate = 28 April 2017 |work = International Business Times |date = 28 April 2017 |deadurl = no |archiveurl = https://web.archive.org/web/20170428032027/http://www.ibtimes.co.uk/ethereum-co-founder-dr-gavin-wood-company-release-parity-bitcoin-1619025 |archivedate = 28 April 2017 }}</ref>

=== Decentralization ===

Bitcoin was designed not to need a central authority{{r|paper}} and the bitcoin network is considered to be decentralized.{{r|primer}}{{r|JSC}}<ref name="ieeesurvey">{{cite journal |last1 = Tschorsch |first1 = Florian |last2 = Scheuermann |first2 = Björn |title = Bitcoin and Beyond: A Technical Survey on Decentralized Digital Currencies |journal = IEEE Communications Surveys & Tutorials |volume = 18 |issue = 3 |pages = 2084–2123 |url = http://ieeexplore.ieee.org/document/7423672/?reload=true |accessdate = 24 October 2017 |deadurl = no |archiveurl = https://web.archive.org/web/20171024161444/http://ieeexplore.ieee.org/document/7423672/?reload=true |archivedate = 24 October 2017 |df = dmy-all |doi=10.1109/comst.2016.2535718|year = 2016 }}</ref><ref name="USoff">{{cite news |url = https://www.washingtonpost.com/news/the-switch/wp/2013/11/21/heres-how-bitcoin-charmed-washington/# |title = Here's how Bitcoin charmed Washington |date = 21 November 2013 |first = Timothy B. |last = Lee |work = The Washington Post |accessdate = 10 October 2016 |deadurl = no |archiveurl = https://web.archive.org/web/20170101144528/https://www.washingtonpost.com/news/the-switch/wp/2013/11/21/heres-how-bitcoin-charmed-washington/ |archivedate = 1 January 2017 |df = dmy-all }}</ref><ref name="dh150613">{{cite news |last1 = O'Brien |first1 = Matt |title = The scam called Bitcoin |url = http://www.dailyherald.com/article/20150613/business/150619551/ |accessdate = 20 September 2016 |work = Daily Herald |date = 13 June 2015 |deadurl = no |archiveurl = https://web.archive.org/web/20150616000405/http://www.dailyherald.com/article/20150613/business/150619551 |archivedate = 16 June 2015 |df = dmy-all }}</ref><ref name=kopstein>{{cite news |author1 = Janus Kopfstein |title = The Mission to Decentralize the Internet |url = http://www.newyorker.com/tech/elements/the-mission-to-decentralize-the-internet |accessdate = 30 December 2014 |work = [[The New Yorker]] |date = 12 December 2013 |quote = The network's 'nodes' – users running the bitcoin software on their computers – collectively check the integrity of other nodes to ensure that no one spends the same coins twice. All transactions are published on a shared public ledger, called the 'blockchain'. |deadurl = no |archiveurl = https://web.archive.org/web/20141231031044/http://www.newyorker.com/tech/elements/the-mission-to-decentralize-the-internet |archivedate = 31 December 2014 |df = dmy-all }}</ref> However, researchers have pointed out a visible "trend towards centralization" by the means of miners joining large [[mining pool]]s to minimise the variance of their income.<ref>{{Cite journal|last=Beikverdi|first=A.|last2=Song|first2=J.|date=June 2015|title=Trend of centralization in Bitcoin's distributed network|url=http://ieeexplore.ieee.org/abstract/document/7176229/?reload=true|journal=2015 IEEE/ACIS 16th International Conference on Software Engineering, Artificial Intelligence, Networking and Parallel/Distributed Computing (SNPD)|pages=1–6|doi=10.1109/SNPD.2015.7176229|deadurl=no|archiveurl=https://web.archive.org/web/20180126125601/http://ieeexplore.ieee.org/abstract/document/7176229/?reload=true|archivedate=26 January 2018|isbn=978-1-4799-8676-7}}</ref> According to researchers, other parts of the ecosystem are also "controlled by a small set of entities", notably online wallets and simplified payment verification (SPV) clients.<ref name=":0">{{cite web |last1= Gervais |first1= Arthur |last2= Karame |first2= Ghassan O. |last3= Capkun |first3= Vedran |last4= Capkun |first4= Srdjan |title= Is Bitcoin a Decentralized Currency? |url= https://www.infoq.com/articles/is-bitcoin-a-decentralized-currency/ |accessdate= 11 October 2016 |website= InfoQ |publisher= InfoQ & [[IEEE Computer Society]] |deadurl= no |archiveurl= https://web.archive.org/web/20161010042659/https://www.infoq.com/articles/is-bitcoin-a-decentralized-currency/ |archivedate= 10 October 2016 |df= dmy-all }}</ref>

Because transactions on the network are confirmed by miners, decentralization of the network requires that no single miner or mining pool obtains 51% of the hashing power, which would allow them to [[double-spending|double-spend]] coins, prevent certain transactions from being verified and prevent other miners from earning income.<ref name=":0" /> As of 2013 just six mining pools controlled 75% of overall bitcoin hashing power.<ref name=":0" />

In 2014 mining pool [[Ghash.io]] obtained 51% hashing power which raised significant controversies about the safety of the network. The pool has voluntarily capped their hashing power at 39.99% and requested other pools to act responsibly for the benefit of the whole network.<ref>{{Cite news|url=https://techcrunch.com/2014/07/16/popular-bitcoin-mining-pool-promises-to-restrict-its-compute-power-to-prevent-feared-51-fiasco/|title=Popular Bitcoin Mining Pool Promises To Restrict Its Compute Power To Prevent Feared ‘51%’ Fiasco|last=Wilhelm|first=Alex|work=TechCrunch|accessdate=25 January 2018|deadurl=no|archiveurl=https://web.archive.org/web/20171205042008/https://techcrunch.com/2014/07/16/popular-bitcoin-mining-pool-promises-to-restrict-its-compute-power-to-prevent-feared-51-fiasco/|archivedate=5 December 2017}}</ref>

=== Privacy ===

Bitcoin is [[pseudonymous]], meaning that funds are not tied to real-world entities but rather bitcoin addresses. Owners of bitcoin addresses are not explicitly identified, but all transactions on the blockchain are public. In addition, transactions can be linked to individuals and companies through "idioms of use" (e.g., transactions that spend coins from multiple inputs indicate that the inputs may have a common owner) and corroborating public transaction data with known information on owners of certain addresses.<ref>{{cite web |url = http://www.technologyreview.com/news/518816/mapping-the-bitcoin-economy-could-reveal-users-identities/ |title = Mapping the Bitcoin Economy Could Reveal Users’ Identities |work = MIT Technology Review |date = 5 September 2013 |accessdate = 2 April 2014 |author = Simonite, Tom }}</ref> Additionally, bitcoin exchanges, where bitcoins are traded for traditional currencies, may be required by law to collect personal information.<ref name="5facts">{{cite news |url = https://www.washingtonpost.com/blogs/the-switch/wp/2013/08/21/five-surprising-facts-about-bitcoin-2/ |title = Five surprising facts about Bitcoin |publisher = The Washington Post |date = 21 August 2013 |accessdate = 2 April 2014 |author = Lee, Timothy |deadurl = no |archiveurl = https://web.archive.org/web/20131012035053/http://www.washingtonpost.com/blogs/the-switch/wp/2013/08/21/five-surprising-facts-about-bitcoin-2/ |archivedate = 12 October 2013 |df = dmy-all }}</ref>

To heighten financial privacy, a new bitcoin address can be generated for each transaction.<ref>{{cite web |url = https://www.wired.co.uk/news/archive/2013-06/06/bitcoin-retail |title = How Bitcoin lets you spy on careless companies |publisher = Conde Nast |work = wired.co.uk |date = 6 June 2013 |accessdate = 2 April 2014 |author = McMillan, Robert |deadurl = yes |archiveurl = https://web.archive.org/web/20140209202222/http://www.wired.co.uk/news/archive/2013-06/06/bitcoin-retail |archivedate = 9 February 2014 |df = dmy-all }}</ref> For example, hierarchical deterministic wallets generate [[pseudorandom]] "rolling addresses" for every transaction from a single [[Random seed|seed]], while only requiring a single passphrase to be remembered to recover all corresponding private keys.<ref>{{cite web |url = https://airbitz.co/go/mastering-bitcoin-privacy/ |title = Mastering Bitcoin Privacy |publisher = Airbitz |date = 31 July 2015 |accessdate = 23 February 2016 |author = Potts, Jake |deadurl = no |archiveurl = https://web.archive.org/web/20150810042927/https://airbitz.co/go/mastering-bitcoin-privacy/ |archivedate = 10 August 2015 |df = dmy-all }}</ref> Researchers at [[Stanford University]] and [[Concordia University]] have also shown that bitcoin exchanges and other entities can prove assets, [[Liability (financial accounting)|liabilities]], and [[solvency]] without revealing their addresses using [[zero-knowledge proof]]s.<ref>{{cite web |url = https://eprint.iacr.org/2015/1008.pdf |title = Provisions: Privacy-preserving proofs of solvency for Bitcoin exchanges |publisher = [[International Association for Cryptologic Research]] |date = 26 October 2015 |accessdate = 23 February 2016 |author1 = Gaby G. Dagher |author2 = Benedikt Bünz |author3 = Joseph Bonneau |author4 = Jeremy Clark |author5 = [[Dan Boneh]] |deadurl = no |archiveurl = https://web.archive.org/web/20160310104206/http://eprint.iacr.org/2015/1008.pdf |archivedate = 10 March 2016 |df = dmy-all }}</ref> "Bulletproofs," a version of Confidential Transactions proposed by Greg Maxwell, have been tested by Professor [[Dan Boneh]] of Stanford.<ref>{{cite web |url = https://bitcoinmagazine.com/articles/how-bulletproofs-could-make-bitcoin-privacy-less-costly/ |publisher = bitcoin magazine|date = 20 December 2017 |accessdate = 22 February 2018 |author1 = Michiel Mulders |title = How Bulletproofs Could Make Bitcoin Privacy Less Costly |df = dmy-all }}</ref> Other solutions such Merkelized Abstract Syntax Trees (MAST), pay-to-script-hash (P2SH) with MERKLE-BRANCH-VERIFY, and "Tail Call Execution Semantics", have also been proposed to support private smart contracts.

=== Fungibility ===

Wallets and similar software technically handle all bitcoins as equivalent, establishing the basic level of [[fungibility]]. Researchers have pointed out that the history of each bitcoin is registered and publicly available in the blockchain ledger, and that some users may refuse to accept bitcoins coming from controversial transactions, which would harm bitcoin's fungibility.<ref>{{cite web |first1 = Eli |last1 = Ben-Sasson |first2 = Alessandro |last2 = Chiesa |first3 = Christina |last3 = Garman |first4 = Matthew |last4 = Green |first5 = Ian |last5 = Miers |first6 = Eran |last6 = Tromer |first7 = Madars |last7 = Virza |work = 2014 IEEE Symposium on Security and Privacy |title = Zerocash: Decentralized Anonymous Payments from Bitcoin |url = http://zerocash-project.org/media/pdf/zerocash-oakland2014.pdf |date = 2014 |accessdate = 31 October 2014 |publisher = IEEE computer society |deadurl = no |archiveurl = https://web.archive.org/web/20141014012438/http://zerocash-project.org/media/pdf/zerocash-oakland2014.pdf |archivedate = 14 October 2014 |df = dmy-all }}</ref>

=== Scalability ===
{{Main|Bitcoin scalability problem}}

The blocks in the blockchain were originally limited to 32 [[megabyte]] in size. The block size limit of one [[megabyte]] was introduced by Satoshi Nakamoto in 2010. Eventually the block size limit of one megabyte created problems for transaction processing, such as increasing transaction fees and delayed processing of transactions.<ref>{{cite news |last1 = Orcutt |first1 = Mike |title = Leaderless Bitcoin Struggles to Make Its Most Crucial Decision |url = https://www.technologyreview.com/s/537486/leaderless-bitcoin-struggles-to-make-its-most-crucial-decision/ |accessdate = 22 June 2017 |work = MIT Technology Review |date = 19 May 2015 }}{{cite news |title = Bitcoin Transaction Fees Are Pretty Low Right Now: Heres Why |url=https://bitcoinmagazine.com/articles/bitcoin-transaction-fees-are-pretty-low-right-now-heres-why/ |date = 31 January 2018}}</ref>


Research shows a trend towards centralization in bitcoin as miners join [[Mining pool|pools]] for stable income.<ref name="JEP">{{Cite journal |last1=Rainer Böhme |last2=Nicolas Christin |last3=Benjamin Edelman |last4=Tyler Moore |year=2015 |title=Bitcoin: Economics, Technology, and Governance |journal=[[Journal of Economic Perspectives]] |volume=29 |issue=2 |pages=213–238 |doi=10.1257/jep.29.2.213 |doi-access=free}}</ref>{{rp|215, 219–222}}<ref>{{Cite journal |last1=Tschorsch |first1=Florian |last2=Scheuermann |first2=Björn |year=2016 |title=Bitcoin and Beyond: A Technical Survey on Decentralized Digital Currencies |journal=[[IEEE Communications Surveys and Tutorials]] |volume=18 |issue=3 |pages=2084–2123 |doi=10.1109/comst.2016.2535718 |s2cid=5115101}}</ref>{{rp|3}} If a single miner or pool controls more than 50% of the [[Hashrate|hashing power]], it would allow them to censor transactions and double-spend coins.<ref name=Gervais2014/> In 2014, mining pool [[Ghash.io]] reached 51% mining power, causing safety concerns, but later voluntarily capped its power at 39.99% for the benefit of the whole network.<ref>{{Cite news |last=Wilhelm |first=Alex |title=Popular Bitcoin Mining Pool Promises To Restrict Its Compute Power To Prevent Feared '51%' Fiasco |work=TechCrunch |url=https://techcrunch.com/2014/07/16/popular-bitcoin-mining-pool-promises-to-restrict-its-compute-power-to-prevent-feared-51-fiasco/ |url-status=live |access-date=25 January 2018 |archive-url=https://web.archive.org/web/20171205042008/https://techcrunch.com/2014/07/16/popular-bitcoin-mining-pool-promises-to-restrict-its-compute-power-to-prevent-feared-51-fiasco/ |archive-date=5 December 2017}}</ref> A few entities also dominate other parts of the ecosystem such as the client software, online wallets, and simplified payment verification (SPV) clients.<ref name=Gervais2014/>
On 24 August 2017 (at block 481,824), [[Segregated Witness]] (SegWit) went live. Transactions contain some data which is only used to verify the transaction, and does not otherwise effect the movement of coins. SegWit introduces a new transaction format that moves this data into a new field in a backwards-compatible way. The segregated data, the so-called ''witness'', is not sent to non-SegWit nodes and therefore does not form part of the blockchain as seen by legacy nodes. This lowers the size of the average transaction in such nodes' view, thereby increasing the block size without incurring the hard fork implied by other proposals for block size increases. Thus, per computer scientist Jochen Hoenicke, the actual block capacity depends on the ratio of SegWit transactions in the block, and on the ratio of signature data. Based on his estimate, if the ratio of SegWit transactions is 50%, the block capacity may be 1.25 megabytes. According to Hoenicke, if native SegWit addresses from Bitcoin Core version 0.16.0 are used, and SegWit adoption reaches 90 to 95%, a block size of up to 1.8 megabytes is possible.


== Economics ==
==Economics and usage==
{{Main|Economics of bitcoin}}
{{Main|Economics of bitcoin}}


===Bitcoin's theoretical roots and ideology===
=== Classification ===
{{see also|Crypto-anarchism}}
{{external media | width = 210px | float = right | video1 = [https://www.youtube.com/watch?v=XQqZ9b0S0BY The Declaration Of Bitcoin's Independence], BraveTheWorld, 4:38}}According to the [[European Central Bank]], the decentralization of money offered by bitcoin has its theoretical roots in the [[Austrian school of economics]], especially with [[Friedrich von Hayek]]'s book ''[[The Denationalization of Money]]'', in which he advocates a complete [[free market]] in the production, distribution and management of money to end the monopoly of [[central banks]].<ref>{{cite book |author=European Central Bank |url=http://www.ecb.europa.eu/pub/pdf/other/virtualcurrencyschemes201210en.pdf |title=Virtual Currency Schemes |year=2012 |publisher=[[European Central Bank]] |isbn=978-92-899-0862-7 |archive-url=https://web.archive.org/web/20121106053452/http://www.ecb.europa.eu/pub/pdf/other/virtualcurrencyschemes201210en.pdf |archive-date=6 November 2012 |url-status=live|oclc=1044382974|doi=10.2866/47380 }}</ref>{{rp|22}} Sociologist [[Nigel Dodd]], citing the [[crypto-anarchism|crypto-anarchist]] ''Declaration of Bitcoin's Independence'', argues that the essence of the bitcoin ideology is to remove money from social, as well as governmental, control.<ref>{{cite journal |last1=Dodd |first1=Nigel |date=May 2018 |title=The Social Life of Bitcoin |url=https://eprints.lse.ac.uk/69229/1/Dodd_The%20social%20life%20of%20Bitcoin_author_2017%20LSERO.pdf |journal=Theory, Culture & Society |volume=35 |issue=3 |pages=35–56 |doi=10.1177/0263276417746464 |s2cid=51914607 |issn=0263-2764 |authorlink1=Nigel Dodd |access-date=22 November 2023 |archive-date=22 November 2023 |archive-url=https://web.archive.org/web/20231122163925/https://eprints.lse.ac.uk/69229/1/Dodd_The%20social%20life%20of%20Bitcoin_author_2017%20LSERO.pdf |url-status=live }}</ref> ''[[The Economist]]'' describes bitcoin as "a techno-anarchist project to create an online version of cash, a way for people to transact without the possibility of interference from malicious governments or banks".<ref name="30082018Economist" /> These philosophical ideas initially attracted [[libertarian]]s and [[anarchist]]s.<ref>{{cite news |last=Feuer |first=Alan |date=14 December 2013 |title=The Bitcoin Ideology |work=The New York Times |url=https://www.nytimes.com/2013/12/15/sunday-review/the-bitcoin-ideology.html |url-status=live |access-date=1 July 2018 |archive-url=https://web.archive.org/web/20180701222302/https://www.nytimes.com/2013/12/15/sunday-review/the-bitcoin-ideology.html |archive-date=1 July 2018}}</ref> Economist [[Paul Krugman]] argues that cryptocurrencies like bitcoin are only used by bank skeptics and criminals.{{r|Krugman}}


=== Recognition as a currency and legal status ===
Bitcoin is a [[digital asset]] invented by Satoshi Nakamoto that was designed to work as a currency.{{r|paper|Monetarists}} It is commonly referred to as digital currency,<ref name="primer" />{{rp|1}} [[digital cash]],<ref>{{cite news |url = https://www.nytimes.com/2013/08/01/technology/personaltech/virtual-currency-gains-ground-in-actual-world.html |title = Virtual Currency Gains Ground in Actual World |publisher = The New York Times |date = 31 July 2013 |accessdate = 6 May 2014 |author = Murphy, Kate |quote = A type of digital cash, bitcoins were invented in 2009 and can be sent directly to anyone, anywhere in the world. |deadurl = no |archiveurl = https://web.archive.org/web/20141014012602/http://www.nytimes.com/2013/08/01/technology/personaltech/virtual-currency-gains-ground-in-actual-world.html |archivedate = 14 October 2014 |df = dmy-all }}</ref> [[virtual currency]],<ref name="satoshi unit" /> [[electronic currency]],<ref name="capitalization" /> or cryptocurrency.<ref name="currencydispute" />
{{Legal status of bitcoin|300px}}
[[Money]] serves three purposes: a [[store of value]], a [[medium of exchange]], and a [[unit of account]].<ref name="econ315">{{Cite news |date=15 March 2014 |title=Free Exchange. Money from nothing. Chronic deflation may keep Bitcoin from displacing its rivals. |newspaper=The Economist |url=https://www.economist.com/news/finance-and-economics/21599053-chronic-deflation-may-keep-bitcoin-displacing-its-fiat-rivals-money |url-status=live |access-date=25 March 2014 |archive-url=https://web.archive.org/web/20140325085119/http://www.economist.com/news/finance-and-economics/21599053-chronic-deflation-may-keep-bitcoin-displacing-its-fiat-rivals-money |archive-date=25 March 2014}}</ref> According to ''The Economist'' in 2014, bitcoin functions best as a medium of exchange.<ref name=econ315 /> In 2015, ''The Economist'' noted that bitcoins had three qualities useful in a currency: they are "hard to earn, limited in supply and easy to verify".<ref>{{Cite news |date=13 January 2015 |title=The magic of mining |newspaper=[[The Economist]] |url=https://www.economist.com/news/business/21638124-minting-digital-currency-has-become-big-ruthlessly-competitive-business-magic |url-status=live |access-date=13 January 2015 |archive-url=https://web.archive.org/web/20150112165531/http://www.economist.com/news/business/21638124-minting-digital-currency-has-become-big-ruthlessly-competitive-business-magic |archive-date=12 January 2015}}</ref> However, a 2018 assessment by ''The Economist'' stated that cryptocurrencies met none of these three criteria.<ref name="30082018Economist">{{Cite news |date=30 August 2018 |title=Bitcoin and other cryptocurrencies are useless |newspaper=The Economist |url=https://www.economist.com/leaders/2018/08/30/bitcoin-and-other-cryptocurrencies-are-useless |url-status=live |access-date=4 September 2018 |archive-url=https://web.archive.org/web/20180904040905/https://www.economist.com/leaders/2018/08/30/bitcoin-and-other-cryptocurrencies-are-useless |archive-date=4 September 2018 }}</ref> Per some researchers, {{as of|2015|lc=yes}}, bitcoin functions more as a [[payment system]] than as a currency.<ref name=JEP/> In 2014, economist [[Robert J. Shiller]] wrote that bitcoin has potential as a unit of account for measuring the relative value of goods, as with Chile's [[Unidad de Fomento]], but that "Bitcoin in its present form&nbsp;... doesn't really solve any sensible economic problem".<ref name="Shiller">{{Cite news |last=Shiller |first=Robert |date=1 March 2014 |title=In Search of a Stable Electronic Currency |work=The New York Times |url=https://www.nytimes.com/2014/03/02/business/in-search-of-a-stable-electronic-currency.html |url-status=live |archive-url=https://web.archive.org/web/20141024120222/http://www.nytimes.com/2014/03/02/business/in-search-of-a-stable-electronic-currency.html |archive-date=24 October 2014}}</ref> François R. Velde, Senior Economist at the [[Chicago Fed]], described bitcoin as "an elegant solution to the problem of creating a digital currency".<ref>{{cite web |last=Velde |first=François |date=December 2013 |title=Bitcoin: A primer |url=https://www.chicagofed.org/digital_assets/publications/chicago_fed_letter/2013/cfldecember2013_317.pdf |url-status=live |archive-url=https://web.archive.org/web/20141026065254/http://www.chicagofed.org/digital_assets/publications/chicago_fed_letter/2013/cfldecember2013_317.pdf |archive-date=26 October 2014 |access-date=3 September 2016 |website=Chicago Fed letter |publisher=[[Federal Reserve Bank of Chicago]] |page=4 |issue=317}}</ref> David Andolfatto, Vice President at the [[Federal Reserve Bank of St. Louis]], stated that bitcoin is a threat to the establishment, which he argues is a good thing for the [[Federal Reserve System]] and other [[central bank]]s, because it prompts these institutions to operate sound policies.<ref>{{cite news |last=Wile|first= Rob |date=6 April 2014 |title=St. Louis Fed Economist: Bitcoin Could Be A Good Threat To Central Banks |url=http://www.businessinsider.com/interview-with-david-andolfatto-2014-4 |url-status=live |archive-url=https://web.archive.org/web/20150924095030/http://www.businessinsider.com/interview-with-david-andolfatto-2014-4 |archive-date=24 September 2015 |access-date=16 April 2014 |work=[[Business Insider]]}}</ref>


The [[Legality of cryptocurrency by country or territory|legal status of bitcoin]] varies substantially from one jurisdiction to another. Because of its decentralized nature and its global presence, regulating bitcoin is difficult. However, the use of bitcoin can be criminalized, and shutting down exchanges and the peer-to-peer economy in a given country would constitute a [[de facto]] ban.<ref>{{cite news |first=Jacob |last=Weindling |date=18 September 2017 |title=China May Be Gearing Up to Ban Bitcoin |url=https://www.pastemagazine.com/politics/bitcoin/china-may-be-gearing-up-to-ban-bitcoin |work=[[Paste (magazine)|Paste]] |access-date=22 November 2023 |archive-date=22 November 2023 |archive-url=https://web.archive.org/web/20231122163924/https://www.pastemagazine.com/politics/bitcoin/china-may-be-gearing-up-to-ban-bitcoin |url-status=live }}</ref> The [[Cryptocurrency and crime|use of bitcoin by criminals]] has attracted the attention of financial regulators, legislative bodies, and law enforcement.<ref>{{Cite news |last=Lavin|first= Tim |date=8 August 2013 |title=The SEC Shows Why Bitcoin Is Doomed |work=[[Bloomberg News]] |url=http://www.bloombergview.com/articles/2013-08-08/did-the-sec-just-validate-bitcoin-no- |url-status=live |access-date=20 October 2013 |archive-url=https://web.archive.org/web/20140325214514/http://www.bloombergview.com/articles/2013-08-08/did-the-sec-just-validate-bitcoin-no- |archive-date=25 March 2014}}</ref> Nobel-prize winning economist [[Joseph Stiglitz]] says that bitcoin's anonymity encourages [[money laundering]] and other crimes.<ref>{{Cite news |last=Montag |first=Ali |date=9 July 2018 |title=Nobel-winning economist: Authorities will bring down 'hammer' on bitcoin |publisher=CNBC |url=https://www.cnbc.com/2018/07/09/nobel-prize-winning-economist-joseph-stiglitz-criticizes-bitcoin.html |url-status=live |access-date=11 July 2018 |archive-url=https://web.archive.org/web/20180711200915/https://www.cnbc.com/2018/07/09/nobel-prize-winning-economist-joseph-stiglitz-criticizes-bitcoin.html |archive-date=11 July 2018}}</ref> This is the main justification behind bitcoin bans.<ref name=SunYin2019/> {{As of|2021|11}}, nine countries applied an absolute ban (Algeria, Bangladesh, China, Egypt, Iraq, Morocco, Nepal, Qatar, and Tunisia) while another 42 countries had an implicit ban.<ref name=LOC2021>{{cite web |title=Regulation of Cryptocurrency Around the World: November 2021 Update |url=https://tile.loc.gov/storage-services/service/ll/llglrd/2021687419/2021687419.pdf |publisher=United States Library of Congress |access-date=28 December 2022 |archive-date=24 December 2021 |archive-url=https://web.archive.org/web/20211224043203/https://tile.loc.gov/storage-services/service/ll/llglrd/2021687419/2021687419.pdf |url-status=live }}</ref>{{Update inline|reason=Many things have changed since Nov 2021.|date=November 2023}} Bitcoin is only [[legal tender]] in [[El Salvador]].<ref name=BTCSVSept7FT/>
Bitcoin does not necessarily work well as a [[currency]].<ref name="currencydispute">{{cite news |url = https://www.usatoday.com/story/money/business/2014/04/25/ozy-bitcoin-africa-currency/8148853/ |title = How bitcoin is moving money in Africa |publisher = USA Today |work = usatoday.com |date = 25 April 2014 |accessdate = 25 May 2014 |author = Joyner, April |deadurl = no |archiveurl = https://web.archive.org/web/20140501011649/http://www.usatoday.com/story/money/business/2014/04/25/ozy-bitcoin-africa-currency/8148853/ |archivedate = 1 May 2014 |df = dmy-all }}</ref> Bitcoins have three qualities useful in a currency, according to ''The Economist'' in January 2015: they are "hard to earn, limited in supply and easy to verify".<ref name=ec1305>{{cite news |title = The magic of mining |url = https://www.economist.com/news/business/21638124-minting-digital-currency-has-become-big-ruthlessly-competitive-business-magic |accessdate = 13 January 2015 |work = [[The Economist]] |date = 13 January 2015 |deadurl = no |archiveurl = https://web.archive.org/web/20150112165531/http://www.economist.com/news/business/21638124-minting-digital-currency-has-become-big-ruthlessly-competitive-business-magic |archivedate = 12 January 2015 |df = dmy-all }}</ref> Economists define money as a [[store of value]], a [[medium of exchange]], and a [[unit of account]] and agree that bitcoin does not meet all these criteria.<ref name=econ315 /> {{As of|2014|3}}, the bitcoin market suffered from [[Volatility (finance)|volatility]], limiting the ability of bitcoin to act as a stable store of value, and retailers accepting bitcoin use other currencies as their principal unit of account.<ref name=econ315>{{cite news |title = Free Exchange. Money from nothing. Chronic deflation may keep Bitcoin from displacing its rivals. |url = https://www.economist.com/news/finance-and-economics/21599053-chronic-deflation-may-keep-bitcoin-displacing-its-fiat-rivals-money |accessdate = 25 March 2014 |newspaper = The Economist |date = 15 March 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20140325085119/http://www.economist.com/news/finance-and-economics/21599053-chronic-deflation-may-keep-bitcoin-displacing-its-fiat-rivals-money |archivedate = 25 March 2014 |df = dmy-all }}</ref>


=== General use ===
=== Use for payments ===
[[File:De Waag Bitcoin.jpg|thumb|Café in [[Delft]] accepting Bitcoin]]
{{As of|2018}}, Bitcoin is rarely used in transactions with merchants,<ref name="FT08062018" /> but it is popular to [[Illicit trade|purchase illegal goods]] online.<ref name=TheEconomist20120929>{{Cite news |title=Monetarists Anonymous |newspaper=The Economist |url=https://www.economist.com/finance-and-economics/2012/09/29/monetarists-anonymous |date=29 September 2012 |access-date=22 November 2023 |issn=0013-0613 |archive-date=1 September 2022 |archive-url=https://web.archive.org/web/20220901043303/https://www.economist.com/finance-and-economics/2012/09/29/monetarists-anonymous |url-status=live }}</ref><ref>{{Cite news |last=Ball |first=James |date=22 March 2013 |title=Silk Road: the online drug marketplace that officials seem powerless to stop |language=en-GB |work=The Guardian |url=https://www.theguardian.com/world/2013/mar/22/silk-road-online-drug-marketplace |access-date=22 November 2023 |issn=0261-3077 |archive-date=12 October 2013 |archive-url=https://web.archive.org/web/20131012012106/http://www.theguardian.com/world/2013/mar/22/silk-road-online-drug-marketplace |url-status=live }}</ref> Prices are not usually quoted in bitcoin and trades involve conversions into [[Fiat money|fiat]] currencies.<ref name=JEP/> Commonly cited reasons for not using Bitcoin include high costs, the inability to process [[chargeback]]s, high [[Volatility (finance)|price volatility]], long transaction times, and [[Transaction cost|transaction fees]] (especially for small purchases).<ref name="FT08062018">{{Cite news |last=Murphy |first=Hannah |date=8 June 2018 |title=Who really owns bitcoin now? |work=Financial Times |url=https://www.ft.com/content/29259448-69b3-11e8-b6eb-4acfcfb08c11 |url-status=live |access-date=10 June 2018 |archive-url=https://web.archive.org/web/20180610051316/https://www.ft.com/content/29259448-69b3-11e8-b6eb-4acfcfb08c11 |archive-date=10 June 2018}}</ref><ref>{{cite news |last=Katz |first=Lily |date=12 July 2017 |title=Bitcoin Acceptance Among Retailers Is Low and Getting Lower |url=https://www.bloomberg.com/news/articles/2017-07-12/bitcoin-acceptance-among-retailers-is-low-and-getting-lower |url-status=live |archive-url=https://web.archive.org/web/20180125204553/https://www.bloomberg.com/news/articles/2017-07-12/bitcoin-acceptance-among-retailers-is-low-and-getting-lower |archive-date=25 January 2018 |access-date=25 January 2018 |work=Bloomberg News}}</ref> ''Bloomberg'' reported that bitcoin was being used for large-item purchases on the site [[Overstock.com]] and for cross-border payments to [[freelancer]]s.<ref>{{Cite news |last=Kharif |first=Olga |date=1 August 2018 |title=Bitcoin's Use in Commerce Keeps Falling Even as Volatility Eases |work=Bloomberg News|url=https://www.bloomberg.com/news/articles/2018-08-01/bitcoin-s-use-in-commerce-keeps-falling-even-as-volatility-eases |url-status=live |access-date=2 August 2018 |archive-url=https://web.archive.org/web/20180802073219/https://www.bloomberg.com/news/articles/2018-08-01/bitcoin-s-use-in-commerce-keeps-falling-even-as-volatility-eases |archive-date=2 August 2018}}</ref> {{As of|2015}}, there was little sign of bitcoin use in international [[remittance]]s despite high fees charged by banks and [[Western Union]] who compete in this market.<ref name=JEP/><ref>{{Cite news |last=Chan |first=Bernice |date=16 January 2015 |title=Bitcoin transactions cut the cost of international money transfers |work=[[South China Morning Post]] |url=https://www.scmp.com/lifestyle/technology/article/1679904/bitcoin-transactions-cut-cost-international-money-transfers |url-status=live |access-date=31 May 2019 |archive-url=https://web.archive.org/web/20190531060301/https://www.scmp.com/lifestyle/technology/article/1679904/bitcoin-transactions-cut-cost-international-money-transfers |archive-date=31 May 2019}}</ref>


In September 2021, the [[Bitcoin Law]] made bitcoin [[legal tender]] in [[El Salvador]], alongside the US dollar.<ref name=BTCSVSept7FT/> The adoption has been criticized both internationally and within El Salvador.<ref name=BTCSVSept7FT/><ref>{{cite news |date=2 September 2021 |title=Majority of Salvadorans do not want bitcoin, poll shows |url=https://www.reuters.com/technology/majority-salvadorans-do-not-want-bitcoin-poll-shows-2021-09-02/ |access-date=30 November 2021 |work=Reuters |archive-date=30 November 2021 |archive-url=https://web.archive.org/web/20211130154620/https://www.reuters.com/technology/majority-salvadorans-do-not-want-bitcoin-poll-shows-2021-09-02/ |url-status=live }}</ref> In particular, in 2022, the [[International Monetary Fund]] (IMF) urged El Salvador to reverse its decision.<ref>{{cite news |date=26 January 2022 |title=IMF urges El Salvador to remove Bitcoin as legal tender |work=BBC News |url=https://www.bbc.co.uk/news/world-latin-america-60135552 |access-date=26 January 2022 |archive-date=26 January 2022 |archive-url=https://web.archive.org/web/20220126154241/https://www.bbc.co.uk/news/world-latin-america-60135552 |url-status=live }}</ref> {{As of|2022}}, the use of [[Bitcoin in El Salvador]] remains low: 80% of businesses refused to accept it despite being legally required to.<ref>{{cite report |title=Are Cryptocurrencies Currencies? Bitcoin as Legal Tender in El Salvador |last1=Alvarez |first1=Fernando |last2=Argente |first2=David |publisher=National Bureau of Economic Research |doi=10.3386/w29968 |page= |last3=Van Patten |first3=Diana |doi-access=free |publication-place=Cambridge, MA |year=2022}}</ref> In April 2022, the [[Central African Republic]] (CAR) adopted Bitcoin as legal tender alongside the [[CFA franc]],<ref>{{Cite news |date=28 April 2022 |title=Bitcoin Declared Legal Currency in Central African Republic |work=Bloomberg |url=https://www.bloomberg.com/news/articles/2022-04-28/bitcoin-is-declared-a-legal-currency-in-central-african-republic-l2isppnb |access-date=28 April 2022 |archive-date=28 April 2022 |archive-url=https://web.archive.org/web/20220428141222/https://www.bloomberg.com/news/articles/2022-04-28/bitcoin-is-declared-a-legal-currency-in-central-african-republic-l2isppnb |url-status=live }}</ref> but repealed the reform one year later.<ref>{{Cite web |title=Frequently Asked Questions on Central African Republic |url=https://www.imf.org/en/Countries/CAF/central-african-republic-qandas |access-date=11 August 2023 |website=International Monetary Fund |language=en |archive-date=11 August 2023 |archive-url=https://web.archive.org/web/20230811002905/https://www.imf.org/en/Countries/CAF/central-african-republic-qandas |url-status=live }}</ref>
[[File:Estimated-transaction-volume-usd.svg|thumb|Liquidity (estimated, USD/year, logarithmic scale).<ref name="Blockchain.info" />]]


Bitcoin is also used by some governments. For instance, the [[Government of Iran|Iranian government]] initially opposed cryptocurrencies, but later saw them as an opportunity to circumvent [[Sanctions against Iran|sanctions]].<ref>{{cite news |date=3 November 2020 |title=Iran Is Pivoting to Bitcoin |url=https://www.vice.com/en/article/qjppx3/iran-bitcoin-us-sanctions |work=[[Vice (magazine)|Vice]] |last=Rasool |first=Mohammed |access-date=10 November 2020 |archive-date=3 November 2020 |archive-url=https://web.archive.org/web/20201103235640/https://www.vice.com/en/article/qjppx3/iran-bitcoin-us-sanctions |url-status=live }}</ref> Since 2020, Iran has required local bitcoin miners to sell bitcoin to the [[Central Bank of Iran]], allowing the central bank to use it for imports.<ref name="aawsat202011">{{cite news |date=31 October 2020 |title=Iran: New Crypto Law Requires Selling Bitcoin Directly to Central Bank to Fund Imports |url=https://english.aawsat.com/home/article/2596686/iran-new-crypto-law-requires-selling-bitcoin-directly-central-bank-fund-imports |work=[[Asharq Al-Awsat]] |access-date=31 October 2020 |archive-date=31 October 2020 |archive-url=https://web.archive.org/web/20201031235032/https://english.aawsat.com/home/article/2596686/iran-new-crypto-law-requires-selling-bitcoin-directly-central-bank-fund-imports |url-status=live }}</ref> Some [[administrative division|constituent states]] also accept tax payments in bitcoin, including [[Colorado]] ([[the US|US]])<ref>{{Cite news |date=21 September 2022 |title=Colorado accepts cryptocurrency to pay taxes, moving the state "tech forward" |url=https://www.denverpost.com/2022/09/21/colorado-accepts-cryptocurrency-taxes/ |first=Judith |last=Kohler |work=[[The Denver Post]] |language=en-US |access-date=29 December 2022 |archive-date=29 December 2022 |archive-url=https://web.archive.org/web/20221229090417/https://www.denverpost.com/2022/09/21/colorado-accepts-cryptocurrency-taxes/ |url-status=live }}</ref> and [[Canton of Zug|Zug]] ([[Switzerland]]).<ref>{{Cite news |date=3 September 2020 |title='Crypto Valley' canton to accept Bitcoin for tax payments |url=https://www.swissinfo.ch/eng/business/-crypto-valley--canton-to-accept-bitcoin-for-tax-payments/46010364 |work=[[SWI swissinfo]] |language=en |access-date=22 November 2023 |archive-date=22 November 2023 |archive-url=https://web.archive.org/web/20231122163924/https://www.swissinfo.ch/eng/business/-crypto-valley--canton-to-accept-bitcoin-for-tax-payments/46010364 |url-status=live }}</ref> As of 2023, the US government owned more than $5 billion worth of seized bitcoin.<ref>{{Cite news |last=Huang |first=Vicky Ge |title=Why the U.S. Government Has $5 Billion in Bitcoin |url=https://www.wsj.com/finance/currencies/federal-government-bitcoin-5-billion-78ce0938 |date=15 October 2023 |work=[[The Wall Street Journal]] |language=en-US |access-date=20 February 2024 |archive-date=20 February 2024 |archive-url=https://web.archive.org/web/20240220023509/https://www.wsj.com/finance/currencies/federal-government-bitcoin-5-billion-78ce0938 |url-status=live }}</ref><ref>{{Cite news |last=Castillo |first=Michael del |title=U.S. Government Owns Way More Bitcoin Than Any Other Country–So Why Aren’t They Selling It? |url=https://www.forbes.com/sites/michaeldelcastillo/2023/06/16/us-government-owns-way-more-bitcoin-than-any-other-countryso-why-arent-they-selling-it |date=16 June 2023 |website=[[Forbes]] |language=en |access-date=21 February 2024 |archive-date=21 February 2024 |archive-url=https://web.archive.org/web/20240221155659/https://www.forbes.com/sites/michaeldelcastillo/2023/06/16/us-government-owns-way-more-bitcoin-than-any-other-countryso-why-arent-they-selling-it/ |url-status=live }}</ref>
According to research by [[Cambridge University]], between 2.9 million and 5.8 million unique users used a cryptocurrency wallet in 2017, most of them for bitcoin. The number of users has grown significantly since 2013, when there were 300,000 to 1.3 million users.<ref name="CU2017" />


===Use for investment and status as an economic bubble ===
=== Acceptance by merchants ===
{{Further|Cryptocurrency bubble}}
The overwhelming majority of bitcoin transactions take place on an exchange, rather than being used in transactions with merchants.<ref name="FT08062018"/>
[[File:El Salvador Bitcoin reserves.png|thumb|Government website with El Salvador reserves in May 2024]]
{{As of|2018}}, the overwhelming majority of bitcoin transactions took place on [[cryptocurrency exchange]]s.<ref name="FT08062018" /> Since 2014, regulated bitcoin funds also allow [[Market exposure|exposure]] to the asset or to [[Futures contract|futures]] as an investment.<ref>{{Cite news |date=10 July 2014 |title=Jersey approve Bitcoin fund launch on island |work=BBC News |url=https://www.bbc.com/news/world-europe-jersey-28247796 |url-status=live |access-date=10 July 2014 |archive-url=https://web.archive.org/web/20140710211917/http://www.bbc.com/news/world-europe-jersey-28247796 |archive-date=10 July 2014}}</ref><ref>{{Cite news |date=18 December 2017 |title=Chicago Mercantile Exchange jumps into bitcoin futures |work=CBS News |url=https://www.cbsnews.com/news/chicago-mercantile-exchange-jumps-into-bitcoin-futures/ |url-status=live |access-date=31 May 2019 |archive-url=https://web.archive.org/web/20190531054602/https://www.cbsnews.com/news/chicago-mercantile-exchange-jumps-into-bitcoin-futures/ |archive-date=31 May 2019}}</ref> Individuals and companies such as the [[Winklevoss Capital Management|Winklevoss twins]]<ref>{{Cite news |last=Lee |first=Timothy B. |title=The $11 million in bitcoins the Winklevoss brothers bought is now worth $32 million |newspaper=The Washington Post |url=https://www.washingtonpost.com/news/the-switch/wp/2013/11/09/the-11-million-in-bitcoins-the-winklevoss-brothers-bought-is-now-worth-32-million/ |url-status=live |access-date=11 August 2017 |archive-url=https://web.archive.org/web/20170706111658/https://www.washingtonpost.com/news/the-switch/wp/2013/11/09/the-11-million-in-bitcoins-the-winklevoss-brothers-bought-is-now-worth-32-million/ |archive-date=6 July 2017}}</ref> and [[Elon Musk]]'s companies [[SpaceX]] and [[Tesla, Inc.|Tesla]] have massively invested in Bitcoin.<ref>{{cite news |last1=Maidenberg |first1=Micah |last2=Driebusch |first2=Corrie |last3=Jin |first3=Berber |title=A Rare Look Into the Finances of Elon Musk's Secretive SpaceX |url=https://www.wsj.com/tech/behind-the-curtain-of-elon-musks-secretive-spacex-revenue-growth-and-rising-costs-2c828e2b |access-date=19 November 2023 |work=The Wall Street Journal |date=17 August 2023 |url-access=subscription |archive-date=17 August 2023 |archive-url=https://archive.today/20230817224420/https://www.wsj.com/tech/behind-the-curtain-of-elon-musks-secretive-spacex-revenue-growth-and-rising-costs-2c828e2b |url-status=live }}</ref><ref>{{Cite news |last1=Ostroff |first1=Caitlin |last2=Elliott |first2=Rebecca |date=8 February 2021 |title=Tesla Buys $1.5 Billion in Bitcoin |language=en-US |work=[[The Wall Street Journal]] |url=https://www.wsj.com/articles/tesla-buys-1-5-billion-in-bitcoin-11612791688 |access-date=22 November 2023 |issn=0099-9660 |url-access=subscription |archive-date=6 January 2024 |archive-url=https://web.archive.org/web/20240106160013/https://www.wsj.com/articles/tesla-buys-1-5-billion-in-bitcoin-11612791688 |url-status=live }}</ref> Bitcoin wealth is highly concentrated, with 0.01% holding 27% of in-circulation currency, as of 2021.<ref>{{Cite news |last1=Vigna |first1=Paul |title=Bitcoin's 'One Percent' Controls Lion's Share of the Cryptocurrency's Wealth |work=[[Wall Street Journal]] |date=20 December 2021 |url=https://www.wsj.com/articles/bitcoins-one-percent-controls-lions-share-of-the-cryptocurrencys-wealth-11639996204 |issn=0099-9660 |url-access=subscription |access-date=22 December 2021 |archive-date=22 December 2021 |archive-url=https://web.archive.org/web/20211222180909/https://www.wsj.com/articles/bitcoins-one-percent-controls-lions-share-of-the-cryptocurrencys-wealth-11639996204 |url-status=live }}</ref> {{As of|2023|9}}, El Salvador had $76.5 million worth of bitcoin in its [[Foreign exchange reserves|international reserves]].<ref>{{Cite news |last=Cota |first=Isabella |date=2 September 2023 |title=Two years of bitcoin in Bukele's El Salvador: An opaque experiment with a little-used currency |url=https://english.elpais.com/international/2023-09-02/two-years-of-bitcoin-in-bukeles-el-salvador-an-opaque-experiment-with-a-little-used-currency.html |website=[[El País]] |language=en-us |access-date=24 November 2023 |archive-date=24 November 2023 |archive-url=https://web.archive.org/web/20231124082557/https://english.elpais.com/international/2023-09-02/two-years-of-bitcoin-in-bukeles-el-salvador-an-opaque-experiment-with-a-little-used-currency.html |url-status=live }}</ref>


In 2018, research published in the ''[[Journal of Monetary Economics]]'' concluded that [[Market manipulation|price manipulation]] occurred during the [[Mt. Gox]] bitcoin theft and that the market remained vulnerable to manipulation.<ref>{{cite journal |last1=Gandal |first1=Neil |last2=Hamrick |first2=J.T. |last3=Moore |first3=Tyler |last4=Oberman |first4=Tali |date=May 2018 |title=Price manipulation in the Bitcoin ecosystem |journal=[[Journal of Monetary Economics]] |volume=95 |pages=86–96 |doi=10.1016/j.jmoneco.2017.12.004 |s2cid=26358036 |doi-access=free}}</ref> Research published in ''[[The Journal of Finance]]'' also suggested that trading associated with increases in the amount of the [[Tether (cryptocurrency)|Tether cryptocurrency]] and associated trading at the [[Bitfinex]] exchange accounted for about half of the price increase in bitcoin in late 2017.<ref>{{Cite journal |last1=Griffin |first1=John M. |last2=Shams |first2=Amin |date=August 2020 |title=Is Bitcoin Really Untethered? |url= |journal=[[The Journal of Finance]] |language=en |volume=75 |issue=4 |pages=1913–1964 |doi=10.1111/jofi.12903 |doi-access=free|s2cid=229576274 |issn=0022-1082}}</ref><ref>{{Cite news |last=Popper |first=Nathaniel |date=13 June 2018 |title=Bitcoin's Price Was Artificially Inflated Last Year, Researchers Say |work=The New York Times |url=https://www.nytimes.com/2018/06/13/technology/bitcoin-price-manipulation.html |url-status=live |access-date=13 June 2018 |archive-url=https://web.archive.org/web/20180613100732/https://www.nytimes.com/2018/06/13/technology/bitcoin-price-manipulation.html |archive-date=13 June 2018}}</ref>
Merchants that accept bitcoin as payment may do so through bitcoin payment service providers such as [[Coinbase]] and [[BitPay]].<ref>{{Cite web|url = http://www.bizjournals.com/atlanta/blog/atlantech/2014/09/atlanta-based-bitpay-hooks-up-with-paypal-to.html|title = Atlanta-based BitPay hooks up with PayPal to expand bitcoin adoption|date = 23 September 2014|accessdate = |website = Atlanta Business Chronicle|publisher = |last = Karkaria|first = Urvaksh}}</ref> This allows merchants to avoid the [[volatility risk]] of accepting bitcoin payments directly by converting the received bitcoins to [[fiat money]] through the payment service provider.


Bitcoin, along with other cryptocurrencies, has been described as an [[economic bubble]] by several economists, including [[Nobel Memorial Prize in Economic Sciences|Nobel Prize in Economics]] laureates, such as [[Joseph Stiglitz]],<ref name="Stiglitz">{{Cite news |last=Costelloe |first=Kevin |date=29 November 2017 |title=Bitcoin 'Ought to Be Outlawed,' Nobel Prize Winner Stiglitz Says |work=Bloomberg News |url=https://www.bloomberg.com/news/articles/2017-11-29/bitcoin-ought-to-be-outlawed-nobel-prize-winner-stiglitz-says-jal10hxd |url-status=live |access-date=5 June 2018 |archive-url=https://web.archive.org/web/20180612224313/https://www.bloomberg.com/news/articles/2017-11-29/bitcoin-ought-to-be-outlawed-nobel-prize-winner-stiglitz-says-jal10hxd |archive-date=12 June 2018 |quote=It doesn't serve any socially useful function. |url-access=subscription}}</ref> [[James Heckman]],<ref name=4Nobels/> and [[Paul Krugman]].<ref name=Krugman>{{Cite news |last=Mohamed |first=Theron |title=Nobel economist Paul Krugman slams crypto as mostly useless, after saying it's hugely overpriced and helps criminals |url=https://markets.businessinsider.com/news/currencies/paul-krugman-crypto-bitcoin-price-bubble-crime-cbdc-desantis-banks-2023-5 |date=30 May 2023 |website=[[Business Insider]] |language=en-US |access-date=23 November 2023 |archive-date=23 November 2023 |archive-url=https://web.archive.org/web/20231123131322/https://markets.businessinsider.com/news/currencies/paul-krugman-crypto-bitcoin-price-bubble-crime-cbdc-desantis-banks-2023-5 |url-status=live }}</ref> Another recipient of the prize, [[Robert Shiller]], argues that bitcoin is rather a [[fad]] that may become an [[Asset classes|asset class]]. He describes its price growth as an "epidemic", driven by [[Social contagion|contagious narratives]].<ref>{{Cite news |date=9 June 2021 |title=Don't Call Bitcoin a Bubble. It's an Epidemic |language=en |work=Bloomberg.com |url=https://www.bloomberg.com/opinion/articles/2021-06-09/don-t-call-bitcoin-a-bubble-it-s-an-epidemic |first=John |last=Authers|author-link=John Authers|archive-url=https://web.archive.org/web/20210610021335/https://www.bloomberg.com/opinion/articles/2021-06-09/don-t-call-bitcoin-a-bubble-it-s-an-epidemic |archive-date=10 June 2021 |url-status=live |url-access=subscription}}</ref>
In 2017 and 2018 bitcoin's acceptance among major online retailers included only three out of the top 500 online merchants, down from five in 2016.<ref name="FT08062018">{{cite news |last1=Murphy |first1=Hannah |title=Who really owns bitcoin now? |url=https://www.ft.com/content/29259448-69b3-11e8-b6eb-4acfcfb08c11 |accessdate=10 June 2018 |publisher=Financial Times |date=8 June 2018}}</ref> Reasons for this fall include high transaction fees due to bitcoin's scalability issues, long transaction times and a rise in value making consumers unwilling to spend it.<ref>{{cite web |url=https://www.bloomberg.com/news/articles/2017-07-12/bitcoin-acceptance-among-retailers-is-low-and-getting-lower |title=Bitcoin Acceptance Among Retailers Is Low and Getting Lower |last=Katz |first=Lily |publisher=Bloomberg |date=12 July 2017 |accessdate=25 January 2018 |deadurl=no |archiveurl=https://web.archive.org/web/20180125204553/https://www.bloomberg.com/news/articles/2017-07-12/bitcoin-acceptance-among-retailers-is-low-and-getting-lower |archivedate=25 January 2018 }}</ref>


According to research published in the ''[[International Review of Financial Analysis]]'' in 2018, Bitcoin as an asset is highly volatile and does not behave like any other conventional asset.<ref>{{Cite journal |last1=Klein |first1=Tony |last2=Pham Thu |first2=Hien |last3=Walther |first3=Thomas |date=October 2018 |title=Bitcoin is not the New Gold – A comparison of volatility, correlation, and portfolio performance |url=https://pureadmin.qub.ac.uk/ws/files/155247201/crypto_V2.pdf |journal=International Review of Financial Analysis |language=en |volume=59 |pages=105–116 |doi=10.1016/j.irfa.2018.07.010 |s2cid=158400153 |doi-access= |access-date=24 November 2023 |archive-date=25 November 2023 |archive-url=https://web.archive.org/web/20231125164037/https://pureadmin.qub.ac.uk/ws/files/155247201/crypto_V2.pdf |url-status=live }}</ref> According to one 2022 analysis published in ''[[The Journal of Alternative Investments]]'', bitcoin was less volatile than [[Price of oil|oil]], [[Silver as an investment|silver]], [[United States Treasury security|US Treasuries]], and 190 stocks in the [[S&P 500]] during and after the [[2020 stock market crash]].<ref>{{Cite journal |last=Mazur |first=Mieszko |date=31 March 2022 |title=Misperceptions of Bitcoin Volatility |url= |journal=The Journal of Alternative Investments |language=en |volume=24 |issue=4 |pages=33–44 |doi=10.3905/jai.2022.1.153 |s2cid=247843794 |issn=1520-3255 |doi-access=}}</ref> The term {{wikt-lang|en|hodl}} was created in December 2013 for [[Buy and hold|holding]] Bitcoin rather than selling it during periods of volatility.<ref>{{cite news |last1=Montag |first1=Ali |title='HODL,' 'whale' and 5 other cryptocurrency slang terms explained |url=https://www.cnbc.com/2018/01/23/what-hodl-whale-and-other-cryptocurrency-slang-terms-mean.html |work=CNBC |date=26 August 2018 |access-date=16 March 2021 |archive-date=12 January 2022 |archive-url=https://web.archive.org/web/20220112091630/https://www.cnbc.com/2018/01/23/what-hodl-whale-and-other-cryptocurrency-slang-terms-mean.html |url-status=live }}</ref><ref>{{Cite news |url=https://www.bloomberg.com/news/articles/2020-11-19/what-the-heck-is-hodl-bitcoin-lingo-for-crypto-noobs-quicktake |title=All the Bitcoin Lingo You Need to Know as Crypto Heats Up |last=Hajric |first=Vildana |date=19 November 2020 |work=Bloomberg |access-date=1 December 2020 |url-access=subscription |archive-date=29 November 2020 |archive-url=https://web.archive.org/web/20201129234847/https://www.bloomberg.com/news/articles/2020-11-19/what-the-heck-is-hodl-bitcoin-lingo-for-crypto-noobs-quicktake |url-status=live }}</ref>
=== Financial institutions ===


Economists, investors, and the [[Bank of Estonia|central bank of Estonia]] have described bitcoin as a potential [[Ponzi scheme]].<ref>{{cite news |last=Clinch |first=Matt |date=10 March 2014 |title=Roubini launches stinging attack on bitcoin |url=https://www.cnbc.com/2014/03/10/nches-stinging-attack-on-bitcoin.html |publisher=[[CNBC]] |access-date=22 November 2023 |archive-date=9 July 2022 |archive-url=https://web.archive.org/web/20220709232801/https://www.cnbc.com/2014/03/10/nches-stinging-attack-on-bitcoin.html |url-status=live }}</ref><ref>{{cite news |title=This Billionaire Just Called Bitcoin a 'Pyramid Scheme' |work=[[Fortune (magazine)|Fortune]]|url=https://fortune.com/2017/07/27/howard-marks-bitcoin-pyramid-scheme |url-status=live |archive-url=https://web.archive.org/web/20170924045918/http://fortune.com/2017/07/27/howard-marks-bitcoin-pyramid-scheme/ |archive-date=24 September 2017 |access-date=23 September 2017}}</ref><ref>{{cite news |last1=Ott Ummelas |last2=Milda Seputyte |date=31 January 2014 |title=Bitcoin 'Ponzi' Concern Sparks Warning From Estonia Bank |work=Bloomberg News |url=https://www.bloomberg.com/news/2014-01-30/bitcoin-ponzi-scheme-worry-sparks-estonia-central-bank-caution.html |url-status=live |access-date=1 April 2014 |archive-url=https://web.archive.org/web/20140329214501/http://www.bloomberg.com/news/2014-01-30/bitcoin-ponzi-scheme-worry-sparks-estonia-central-bank-caution.html |archive-date=29 March 2014 |url-access=subscription}}</ref> Legal scholar [[Eric Posner]] disagrees, however, as "a real Ponzi scheme takes fraud; bitcoin, by contrast, seems more like a collective [[delusion]]".<ref>{{Cite news |last=Posner |first=Eric |author-link=Eric Posner |date=11 April 2013 |title=Fool's Gold |language=en-US |work=Slate |url=https://slate.com/news-and-politics/2013/04/bitcoin-is-a-ponzi-scheme-the-internet-currency-will-collapse.html |access-date=22 November 2023 |issn=1091-2339 |archive-date=8 July 2022 |archive-url=https://web.archive.org/web/20220708202651/https://slate.com/news-and-politics/2013/04/bitcoin-is-a-ponzi-scheme-the-internet-currency-will-collapse.html |url-status=live }}</ref> A 2014 [[World Bank]] report also concluded that bitcoin was not a deliberate Ponzi scheme.<ref>{{Cite book |last1=Davradakis |first1=Emmanouil |last2=Santos |first2=Ricardo |url=https://data.europa.eu/doi/10.2867/11329 |title=Blockchain, FinTechs and their relevance for international financial institutions |date=2019 |publisher=[[European Investment Bank]] |doi=10.2867/11329 |isbn=978-92-861-4184-3 |access-date=24 November 2023 |archive-date=21 April 2024 |archive-url=https://web.archive.org/web/20240421113801/https://op.europa.eu/en/publication-detail/-/publication/ae472145-237a-11e9-8d04-01aa75ed71a1/language-en |url-status=live }}</ref>
Bitcoins can be bought on [[digital currency exchange]]s. According to [[Tony Gallippi]], a co-founder of [[BitPay]], "banks are scared to deal with bitcoin companies, even if they really want to".<ref name=scaredbankers>{{cite news |url = https://www.bloomberg.com/news/2013-12-05/bitcoin-skepticism-by-bankers-from-china-to-u-s-hinders-growth.html |title = Bankers Balking at Bitcoin in US as Real-World Obstacles Mount |publisher = Bloomberg |work = bloomberg.com |date = 5 December 2013 |accessdate = 16 April 2014 |author = Dougherty, Carter |deadurl = no |archiveurl = https://web.archive.org/web/20140417033517/http://www.bloomberg.com/news/2013-12-05/bitcoin-skepticism-by-bankers-from-china-to-u-s-hinders-growth.html |archivedate = 17 April 2014 |df = dmy-all }}</ref> In 2014, the [[National Australia Bank]] closed accounts of businesses with ties to bitcoin,<ref>{{cite web |url = https://www.theguardian.com/world/2014/apr/10/bitcoin-dumped-by-national-australia-bank-as-too-risky |title = Bitcoin firms dumped by National Australia Bank as 'too risky' |publisher = The Guardian |work = Australian Associated Press |date = 10 April 2014 |accessdate = 23 February 2015 |deadurl = no |archiveurl = https://web.archive.org/web/20150223011000/http://www.theguardian.com/world/2014/apr/10/bitcoin-dumped-by-national-australia-bank-as-too-risky |archivedate = 23 February 2015 |df = dmy-all }}</ref> and [[HSBC]] refused to serve a hedge fund with links to bitcoin.<ref>{{cite web |url = https://www.bbc.com/news/world-europe-jersey-30261976 |title = HSBC severs links with firm behind Bitcoin fund |publisher = BBC |work = bbc.com |date = 1 December 2014 |accessdate = 9 January 2015 |author = Weir, Mike |deadurl = no |archiveurl = https://web.archive.org/web/20150203210318/http://www.bbc.com/news/world-europe-jersey-30261976 |archivedate = 3 February 2015 |df = dmy-all }}</ref> Australian banks in general have been reported as closing down bank accounts of operators of businesses involving the currency;<ref name="afr.com">{{Cite web |title = ACCC investigating why banks are closing bitcoin companies' accounts |url = http://www.afr.com/technology/accc-investigating-why-banks-are-closing-bitcoin-companies-accounts-20151018-gkc5iv |website = Financial Review |accessdate = 28 January 2016 |deadurl = no |archiveurl = https://web.archive.org/web/20160211070834/http://www.afr.com/technology/accc-investigating-why-banks-are-closing-bitcoin-companies-accounts-20151018-gkc5iv |archivedate = 11 February 2016 |df = dmy-all }}</ref> this has become the subject of an investigation by the [[Australian Competition and Consumer Commission]].<ref name="afr.com" /> Nonetheless, Australian banks have trialled trading between each other using the blockchain technology on which bitcoin is based.<ref>{{Cite web |title = CBA tests blockchain trading with 10 global banks |url = http://www.smh.com.au/business/banking-and-finance/commonwealth-bank-of-australia-tests-blockchain-trading-with-10-global-banks-20160120-gmalvp.html |website = The Sydney Morning Herald |accessdate = 28 January 2016 |deadurl = no |archiveurl = https://web.archive.org/web/20160124022108/http://www.smh.com.au/business/banking-and-finance/commonwealth-bank-of-australia-tests-blockchain-trading-with-10-global-banks-20160120-gmalvp.html |archivedate = 24 January 2016 |df = dmy-all }}</ref>


==See also==
Plans were announced to include a bitcoin futures option on the [[Chicago Mercantile Exchange]] in 2017.<ref>{{cite web |url = https://cointelegraph.com/news/bitcoin-shatters-7k-barrier-after-futures-trading-announcement-by-cme-group |title = Bitcoin Shatters $7k Barrier After Futures Trading Announcement by CME Group |publisher = |deadurl = no |archiveurl = https://web.archive.org/web/20171102153354/https://cointelegraph.com/news/bitcoin-shatters-7k-barrier-after-futures-trading-announcement-by-cme-group |archivedate = 2 November 2017 |df = dmy-all }}</ref> Trading in bitcoin futures was announced to begin on 10 December 2017.<ref>{{cite web |url=https://www.scribd.com/document/366280511/Cboe-Plans-December-10-Launch-of-Bitcoin-Futures-Trading |title=Archived copy |accessdate=16 December 2017 |deadurl=no |archiveurl=https://web.archive.org/web/20180123163015/https://www.scribd.com/document/366280511/Cboe-Plans-December-10-Launch-of-Bitcoin-Futures-Trading |archivedate=23 January 2018 }}</ref>

=== As an investment ===

The [[Winklevoss twins]] have invested into bitcoins. In 2013 ''The Washington Post'' reported a claim that they owned 1% of all the bitcoins in existence at the time.<ref>{{cite news |last1 = Lee |first1 = Timothy B. |title = The $11 million in bitcoins the Winklevoss brothers bought is now worth $32 million |url = https://www.washingtonpost.com/news/the-switch/wp/2013/11/09/the-11-million-in-bitcoins-the-winklevoss-brothers-bought-is-now-worth-32-million/ |accessdate = 11 August 2017 |work = The Switch |publisher = The Washington Post |deadurl = no |archiveurl = https://web.archive.org/web/20170706111658/https://www.washingtonpost.com/news/the-switch/wp/2013/11/09/the-11-million-in-bitcoins-the-winklevoss-brothers-bought-is-now-worth-32-million/ |archivedate = 6 July 2017 |df = dmy-all }}</ref>

Other methods of investment are bitcoin funds. The first regulated bitcoin fund was established in Jersey in July 2014 and approved by the Jersey Financial Services Commission.<ref name="BitcoinJersey">{{cite news |title = Jersey approve Bitcoin fund launch on island |url = https://www.bbc.com/news/world-europe-jersey-28247796 |date = 10 July 2014 |accessdate = 10 July 2014 |publisher = BBC news |deadurl = no |archiveurl = https://web.archive.org/web/20140710211917/http://www.bbc.com/news/world-europe-jersey-28247796 |archivedate = 10 July 2014 |df = dmy-all }}</ref>

In 2013 and 2014, the [[European Banking Authority]]<ref name="ebawarn">{{cite web |url = http://www.eba.europa.eu/documents/10180/16136/EBA+Warning+on+Virtual+Currencies.pdf |archiveurl = https://www.webcitation.org/6MCBOsSXG?url=http://www.eba.europa.eu/documents/10180/16136/EBA+Warning+on+Virtual+Currencies.pdf |archivedate = 28 December 2013 |title = Warning to consumers on virtual currencies |publisher = European Banking Authority |date = 12 December 2013 |accessdate = 23 December 2013 |deadurl = yes |df = dmy }}</ref> and the [[Financial Industry Regulatory Authority]] (FINRA), a United States [[self-regulatory organization]],<ref name="finrawarn">{{cite news |url = https://www.reuters.com/article/2014/03/11/us-bitcoin-finra-idUSBREA2A1OJ20140311 |title = Beware Bitcoin: US brokerage regulator. |author = Jonathan Stempel |date = 11 March 2014 |accessdate = 14 March 2014 |publisher = reuters.com |deadurl = no |archiveurl = https://web.archive.org/web/20140315093640/http://www.reuters.com/article/2014/03/11/us-bitcoin-finra-idUSBREA2A1OJ20140311 |archivedate = 15 March 2014 |df = dmy-all }}</ref> warned that investing in bitcoins carries significant risks. Forbes named bitcoin the best investment of 2013.<ref>{{Cite news |url = https://www.forbes.com/sites/kashmirhill/2013/12/26/how-you-should-have-spent-100-in-2013-hint-bitcoin/ |title = How You Should Have Spent $100 In 2013 (Hint: Bitcoin) |last = Hill |first = Kashmir |date = |work = Forbes |accessdate = 16 February 2015 |deadurl = no |archiveurl = https://web.archive.org/web/20150219043444/http://www.forbes.com/sites/kashmirhill/2013/12/26/how-you-should-have-spent-100-in-2013-hint-bitcoin/ |archivedate = 19 February 2015 }}</ref> In 2014, Bloomberg named bitcoin one of its worst investments of the year.<ref name=worst>{{cite news |url = https://www.bloomberg.com/news/2014-12-22/the-best-and-worst-investments-of-2014.html |title = The Best and Worst Investments of 2014 |publisher = Bloomberg LP |work = bloomberg.com |date = 23 December 2014 |accessdate = 9 January 2015 |author = Steverman, Ben |deadurl = no |archiveurl = https://web.archive.org/web/20150109122649/http://www.bloomberg.com/news/2014-12-22/the-best-and-worst-investments-of-2014.html |archivedate = 9 January 2015 |df = dmy-all }}</ref> In 2015, bitcoin topped Bloomberg's currency tables.<ref>{{cite news |last1 = Gilbert |first1 = Mark |title = Bitcoin Won 2015. Apple ... Did Not |url = http://www.bloombergview.com/articles/2015-12-29/bitcoin-won-in-2015-but-apple-lost-big |accessdate = 29 December 2015 |publisher = Bloomberg |date = 29 December 2015 |deadurl = no |archiveurl = https://web.archive.org/web/20151229200002/http://www.bloombergview.com/articles/2015-12-29/bitcoin-won-in-2015-but-apple-lost-big |archivedate = 29 December 2015 |df = dmy-all }}</ref>

According to bitinfocharts.com, in 2017 there are 9,272 bitcoin wallets with more than $1 million worth of bitcoins.<ref>{{Cite web |url = https://bitinfocharts.com/top-100-richest-bitcoin-addresses.html |title = Top 100 Richest Bitcoin Addresses and Bitcoin distribution |website = bitinfocharts.com |accessdate = 14 October 2017 |deadurl = no |archiveurl = https://web.archive.org/web/20171015082601/https://bitinfocharts.com/top-100-richest-bitcoin-addresses.html |archivedate = 15 October 2017 }}</ref> The exact number of bitcoin millionaires is uncertain as a single person can have more than one bitcoin wallet.

=== Venture capital ===

[[Venture capital]]ists, such as [[Peter Thiel]]'s [[Founders Fund]], which invested {{currency|3|USD}} million in [[BitPay]], do not purchase bitcoins themselves, but instead fund bitcoin infrastructure that provides payment systems to merchants, exchanges, wallet services, etc.<ref name="mtr20130612">{{cite news |url = http://www.technologyreview.com/news/515391/bitcoin-millionaires-become-investing-angels/ |title = Bitcoin Millionaires Become Investing Angels |work = Computing News |publisher = [[MIT Technology Review]] |date = 12 June 2013 |accessdate = 13 June 2013 |author = Simonite, Tom }}</ref> In 2012, an incubator for bitcoin-focused start-ups was founded by Adam Draper, with financing help from his father, venture capitalist [[Timothy C. Draper|Tim Draper]], one of the largest bitcoin holders after winning an auction of 30,000 bitcoins,<ref name=wsj1214>{{cite news |author1 = Robin Sidel |title = Ten-hut! Bitcoin Recruits Snap To |url = https://www.wsj.com/news/articles/SB21659981523255993497704580305120918936264?mg=reno64-wsj&url=http%3A%2F%2Fonline.wsj.com%2Farticle%2FSB21659981523255993497704580305120918936264.html |accessdate = 9 December 2014 |work = Wall Street Journal |publisher = Dow Jones & Company |date = 1 December 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20150227214546/http://www.wsj.com/news/articles/SB21659981523255993497704580305120918936264?mg=reno64-wsj&url=http%3A%2F%2Fonline.wsj.com%2Farticle%2FSB21659981523255993497704580305120918936264.html |archivedate = 27 February 2015 |df = dmy-all }}</ref> at the time called 'mystery buyer'.<ref name=guard714>{{cite news |title = Silk Road's legacy 30,000 bitcoin sold at auction to mystery buyers |author = Alex Hern |url = https://www.theguardian.com/technology/2014/jul/01/silk-road-bitcoin-auction |publisher = The Guardian |date = 1 July 2014 |accessdate = 31 October 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20141023190952/http://www.theguardian.com/technology/2014/jul/01/silk-road-bitcoin-auction |archivedate = 23 October 2014 |df = dmy-all }}</ref> The company's goal is to fund 100 bitcoin businesses within 2–3 years with $10,000 to $20,000 for a 6% stake.<ref name="wsj1214" /> Investors also invest in bitcoin mining.<ref>{{cite news |url = http://www.redherring.com/finance/coinseed-raises-7-5m-invests-5m-in-bitcoin-mining-hardware-investment-round-up/ |title = CoinSeed raises $7.5m, invests $5m in Bitcoin mining hardware – Investment Round Up |work = Red Herring |date = 24 January 2014 |accessdate = 9 March 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20140309042510/http://www.redherring.com/finance/coinseed-raises-7-5m-invests-5m-in-bitcoin-mining-hardware-investment-round-up/ |archivedate = 9 March 2014 |df = dmy-all }}</ref> According to a 2015 study by [[Paolo Tasca]], bitcoin startups raised almost $1 billion in three years (Q1 2012 – Q1 2015).<ref>{{cite journal |last1 = Tasca |first1 = Paolo |title = Digital Currencies: Principles, Trends, Opportunities, and Risks |date = 7 September 2015 |ssrn = 2657598 |accessdate = |publisher = Social Science Research Network }}</ref>

=== Price and volatility ===

[[File:Bitcoin price and volatility.svg|thumb|Price{{efn|name=BTCinUSD|The price of 1 bitcoin in US dollars.}} ''(left y-axis, logarithmic scale)'' and volatility{{efn|Volatility is calculated on a yearly basis.}} ''(right y-axis)''.<ref name="Blockchain.info" />]]

The price of bitcoins has gone through cycles of appreciation and depreciation referred to by some as [[Economic bubble|bubbles]] and busts.<ref>{{cite news |url = https://www.forbes.com/sites/jessecolombo/2013/12/19/bitcoin-may-be-following-this-classic-bubble-stages-chart/ |title = Bitcoin May Be Following This Classic Bubble Stages Chart |publisher = Forbes |date = 19 December 2013 |accessdate = 7 January 2014 |first = Jesse |last = Colombo |deadurl = no |archiveurl = https://web.archive.org/web/20131220094917/http://www.forbes.com/sites/jessecolombo/2013/12/19/bitcoin-may-be-following-this-classic-bubble-stages-chart/ |archivedate = 20 December 2013 |df = dmy-all }}</ref><ref>{{cite web |url = https://www.theguardian.com/commentisfree/2013/apr/03/bitcoin-currency-bubble-crash-not-rocking-financial-markets |title = Confused about Bitcoin? It's 'the Harlem Shake of currency' |publisher = The Guardian |work = theguardian.com |date = 3 April 2013 |accessdate = 2 May 2014 |author = Moore, Heidi |deadurl = no |archiveurl = https://web.archive.org/web/20140301083816/http://www.theguardian.com/commentisfree/2013/apr/03/bitcoin-currency-bubble-crash-not-rocking-financial-markets |archivedate = 1 March 2014 |df = dmy-all }}</ref> In 2011, the value of one bitcoin rapidly rose from about US$0.30 to US$32 before returning to US$2.<ref name="Leebubble">{{cite news |url = https://www.washingtonpost.com/blogs/the-switch/wp/2013/11/05/when-will-the-people-who-called-bitcoin-a-bubble-admit-they-were-wrong |title = When will the people who called Bitcoin a bubble admit they were wrong |publisher = The Washington Post |date = 5 November 2013 |accessdate = 10 January 2014 |author = Lee, Timothy |deadurl = no |archiveurl = https://web.archive.org/web/20140111011839/http://www.washingtonpost.com/blogs/the-switch/wp/2013/11/05/when-will-the-people-who-called-bitcoin-a-bubble-admit-they-were-wrong/ |archivedate = 11 January 2014 |df = dmy-all }}</ref> In the latter half of 2012 and during the [[2012–13 Cypriot financial crisis]], the bitcoin price began to rise,<ref>{{cite web |last = Liu |first = Alec |url = http://motherboard.vice.com/blog/cyprus-spain-when-governments-take-your-money-bitcoin-looks-really-good |title = When Governments Take Your Money, Bitcoin Looks Really Good |publisher = Motherboard |date = 19 March 2013 |accessdate = 7 January 2014 |deadurl = yes |archiveurl = https://web.archive.org/web/20140207194506/http://motherboard.vice.com/blog/cyprus-spain-when-governments-take-your-money-bitcoin-looks-really-good |archivedate = 7 February 2014 |df = dmy-all }}</ref> reaching a high of US$266 on 10 April 2013, before crashing to around US$50.<ref>{{cite news |url = https://www.forbes.com/sites/timothylee/2013/04/11/an-illustrated-history-of-bitcoin-crashes/ |title = An Illustrated History Of Bitcoin Crashes |publisher = Forbes |date = 11 April 2013 |accessdate = 7 January 2014 |first = Timothy B. |last = Lee |deadurl = no |archiveurl = https://wayback.archive-it.org/all/20150920154402/http://www.forbes.com/sites/timothylee/2013/04/11/an-illustrated-history-of-bitcoin-crashes/ |archivedate = 20 September 2015 |df = dmy-all }}</ref> On 29 November 2013, the cost of one bitcoin rose to a peak of US$1,242.<ref>{{cite news |url = http://money.cnn.com/2013/11/29/investing/bitcoin-gold/index.html |title = Bitcoin worth almost as much as gold |author = Ben Rooney |date = 29 November 2013 |publisher = CNN |accessdate = 31 October 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20141026213248/http://money.cnn.com/2013/11/29/investing/bitcoin-gold/index.html |archivedate = 26 October 2014 |df = dmy-all }}</ref> In 2014, the price fell sharply, and as of April remained depressed at little more than half 2013 prices. {{As of|2014|August}} it was under US$600.<ref>{{cite web |url = http://www.nasdaq.com/article/bitcoin-prices-remain-below-600-amid-bearish-chart-signals-cm376685 |title = Bitcoin prices remain below $600 amid bearish chart signals |publisher = nasdaq.com |date = August 2014 |accessdate = 31 October 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20141014012642/http://www.nasdaq.com/article/bitcoin-prices-remain-below-600-amid-bearish-chart-signals-cm376685 |archivedate = 14 October 2014 |df = dmy-all }}</ref>
During their time as bitcoin developers, Gavin Andresen<ref>{{cite web |title = Bitcoin's History of Crushing Speculators |author = Dan Caplinger |publisher = [[The Motley Fool]] |date = 4 April 2013 |accessdate = 7 January 2014 |url = http://www.fool.com/retirement/general/2013/04/04/bitcoins-history-of-crushing-speculators.aspx |deadurl = no |archiveurl = https://web.archive.org/web/20140107121554/http://www.fool.com/retirement/general/2013/04/04/bitcoins-history-of-crushing-speculators.aspx |archivedate = 7 January 2014 |df = dmy-all }}</ref> and Mike Hearn<ref>{{cite news |url = https://www.bbc.co.uk/news/magazine-25332746 |title = Bitcoin: Price v hype |publisher = BBC |work = bbc.com |date = 13 December 2013 |accessdate = 23 December 2013 |author = Barford, Vanessa |deadurl = no |archiveurl = https://web.archive.org/web/20131219213618/http://www.bbc.co.uk/news/magazine-25332746 |archivedate = 19 December 2013 |df = dmy-all }}</ref> warned that bubbles may occur.

According to [[Mark T. Williams]], {{as of | 2014 | lc = y}}, bitcoin has [[volatility (finance)|volatility]] seven times greater than gold, eight times greater than the [[S&P 500]], and 18 times greater than the US dollar.<ref>{{cite web |url = http://management.bu.edu/files/2014/10/Wlliams-World-Bank-10-21-2014.pdf |title = Virtual Currencies – Bitcoin Risk |publisher = Boston University |work = World Bank Conference Washington DC |date = 21 October 2014 |accessdate = 11 November 2014 |author = Williams, Mark T. |deadurl = no |archiveurl = https://web.archive.org/web/20141111095526/http://management.bu.edu/files/2014/10/Wlliams-World-Bank-10-21-2014.pdf |archivedate = 11 November 2014 |df = dmy-all }}</ref>

== Legal status, tax and regulation ==
{{Main|Legality of bitcoin by country or territory}}

Because of bitcoin's decentralized nature, nation-states cannot shut down the network or alter its technical rules.<ref>{{cite web |title = It's Impossible to Kill Bitcoin, Says Former Chief of Govt-Owned Bank of China – CryptoCoinsNews |url = https://www.cryptocoinsnews.com/former-pboc-governor-its-impossible-to-kill-bitcoin/ |website = CryptoCoinsNews |accessdate = 30 November 2017 |date = 14 February 2017 |deadurl = no |archiveurl = https://web.archive.org/web/20171201081909/https://www.cryptocoinsnews.com/former-pboc-governor-its-impossible-to-kill-bitcoin/ |archivedate = 1 December 2017 |df = dmy-all }}</ref> However, the use of bitcoin can be criminalized, and shutting down exchanges and the peer-to-peer economy in a given country would constitute a "de facto ban".<ref>{{cite web |title = China May Be Gearing Up to Ban Bitcoin |url = https://www.pastemagazine.com/articles/2017/09/china-may-be-gearing-up-to-ban-bitcoin.html |website = pastemagazine.com |accessdate = 6 October 2017 |quote = The decentralized nature of bitcoin is such that it is impossible to “ban” the cryptocurrency, but if you shut down exchanges and the peer-to-peer economy running on bitcoin, it’s a de facto ban. |deadurl = no |archiveurl = https://web.archive.org/web/20171003224721/https://www.pastemagazine.com/articles/2017/09/china-may-be-gearing-up-to-ban-bitcoin.html |archivedate = 3 October 2017 |df = dmy-all }}</ref>
The legal status of bitcoin varies substantially from country to country and is still undefined or changing in many of them. While some countries have explicitly allowed its use and trade, others have banned or restricted it. Regulations and bans that apply to bitcoin probably extend to similar cryptocurrency systems.<ref>{{cite journal |last1 = Tasca |first1 = Paolo |title = Digital Currencies: Principles, Trends, Opportunities, and Risks |date = 7 September 2015 |doi = |ssrn = 2657598 |accessdate = |publisher = Social Science Research Network }}</ref>

Bitcoin made its first historic appearance in a [[U.S. Supreme Court]] opinion (on Wisconsin Central Ltd. v. United States) regarding the changing definition of money on 21 June 2018.<ref>{{Cite news|url=https://www.businessinsider.com.au/the-us-supreme-court-just-spoke-about-a-bitcoin-future-for-the-first-time-2018-6|title=The US Supreme Court just spoke about a bitcoin future for the first time|last=Farquhar|first=Peter|date=22 June 2018|access-date=22 June 2018}}</ref>

== Criticism ==
{{external media | width = 210px | float = right | video1 = [https://www.youtube.com/watch?v=vo6s1mUjxQQ&list=PLjKKW-ws0BGqpZ5mnL2sGmYc78exHzrKh&index=2 Cryptocurrencies: looking beyond the hype], [[Hyun Song Shin]], [[Bank for International Settlements]], 2:48<ref name="bis report"/> }}
The [[Bank for International Settlements]] summarized many of the criticisms of bitcoin in Chapter V of their 2018 annual report. The criticisms include the lack of stability in bitcoin's price, the "environmental disaster" entailed by high energy consumption, high and variable transactions costs, the poor security and fraud at cryptocurrency exchanges, vulnerability to debasement (from forking), and the influence of miners.<ref name="chapterV">{{cite web |last1=Hyun Song Shin |title=Chapter V. Cryptocurrencies: looking beyond the hype |url=https://www.bis.org/publ/arpdf/ar2018e5.pdf |website=BIS 2018 Annual Economic Report |publisher=Bank for International Settlements |accessdate=19 June 2018 |date=June 2018 |quote=Put in the simplest terms, the quest for decentralised trust has quickly become an environmental disaster.}}</ref><ref name="bis report">{{cite news |last1=Janda |first1=Michael |title=Cryptocurrencies like bitcoin cannot replace money, says Bank for International Settlements |url=http://www.abc.net.au/news/2018-06-18/cryptocurrencies-cannot-replace-money-bis/9879448 |accessdate=18 June 2018 |publisher=ABC (Australia) |date=18 June 2018}}</ref><ref name="LATHiltzik">{{cite news |last1=Hiltzik |first1=Michael |title=Is this scathing report the death knell for bitcoin? |url=http://www.latimes.com/business/hiltzik/la-fi-hiltzik-bitcoin-bank-20180618-story.html |accessdate=19 June 2018 |publisher=Los Angeles Times |date=18 June 2018}}</ref>

=== Identification as a speculative bubble===
{{Main|Cryptocurrency bubble}}

Bitcoin and other [[cryptocurrencies]] have been identified as [[economic bubble]]s by at least eight [[Nobel Memorial Prize in Economic Sciences]] laureates, including [[Paul Krugman]],<ref name="NYTKrugman1">{{cite news |last1=Krugman |first1=Paul |title=Bubble, Bubble, Fraud and Trouble |url=https://www.nytimes.com/2018/01/29/opinion/bitcoin-bubble-fraud.html |accessdate=7 June 2018 |publisher=New York Times |date=29 January 2018}}</ref> [[Robert Shiller]],<ref>{{cite news |last = Shiller |first = Robert |title = In Search of a Stable Electronic Currency |url = https://www.nytimes.com/2014/03/02/business/in-search-of-a-stable-electronic-currency.html?_r=0 |publisher = New York Times |date = 1 March 2014 |accessdate = 31 October 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20141024120222/http://www.nytimes.com/2014/03/02/business/in-search-of-a-stable-electronic-currency.html?_r=0 |archivedate = 24 October 2014 |df = dmy-all }}</ref> [[Joseph Stiglitz]]<ref name ="Stiglitz">{{cite news |last1=Costelloe |first1=Kevin |title=Bitcoin ‘Ought to Be Outlawed,’ Nobel Prize Winner Stiglitz Says |url=https://www.bloomberg.com/news/articles/2017-11-29/bitcoin-ought-to-be-outlawed-nobel-prize-winner-stiglitz-says-jal10hxd |accessdate=5 June 2018 |publisher=Bloomberg |date=29 November 2017 |quote=It doesn’t serve any socially useful function.}}</ref> and [[Richard Thaler]].<ref name="Thaler">{{cite news |title=Economics Nobel prize winner, Richard Thaler: “The market that looks most like a bubble to me is Bitcoin and its brethren” |url=https://econews.pt/2018/01/22/economics-nobel-prize-winner-richard-thaler-the-market-that-looks-most-like-a-bubble-to-me-is-bitcoin-and-its-brethren/ |accessdate=7 June 2018 |publisher=ECO Portuguese Economy |date=22 January 2018}}</ref><ref name="4Nobels">{{cite news |last1=Wolff-Mann |first1=Ethan |title='Only good for drug dealers': More Nobel prize winners snub bitcoin |url=https://finance.yahoo.com/news/good-drug-dealers-nobel-prize-winners-snub-bitcoin-184903784.html |accessdate=7 June 2018 |publisher=Yahoo Finance |date=27 April 2018}}</ref>

Professor [[Nouriel Roubini]] of [[New York University]] has called bitcoin the "mother of all bubbles."<ref>{{Cite web|url=https://www.theguardian.com/technology/2018/feb/02/bitcoin-biggest-bubble-in-history-says-economist-who-predicted-2008-crash|title=Bitcoin biggest bubble in history, says economist who predicted 2008 crash|last=|first=|date=|website=|archive-url=|archive-date=|dead-url=|access-date=}}</ref> Central bankers, including Former Federal Reserve Chairman Alan Greenspan,<ref name=Kearns>{{cite news |url = https://www.bloomberg.com/news/2013-12-04/greenspan-says-bitcoin-a-bubble-without-intrinsic-currency-value.html |title = Greenspan Says Bitcoin a Bubble Without Intrinsic Currency Value |publisher = Bloomberg LP |work = bloomberg.com |date = 4 December 2013 |accessdate = 23 December 2013 |author = Kearns, Jeff |deadurl = no |archiveurl = https://web.archive.org/web/20131229054844/http://www.bloomberg.com/news/2013-12-04/greenspan-says-bitcoin-a-bubble-without-intrinsic-currency-value.html |archivedate = 29 December 2013 |df = dmy-all }}</ref> investors such as [[Warren Buffett]]<ref>{{Cite web |url = https://www.cnbc.com/2014/03/14/buffett-blasts-bitcoin-as-mirage-stay-away.html |title = Bitcoin? Here's what Warren Buffett is saying |last = Crippen |first = Alex |date = 14 March 2014 |website = CNBC |access-date = 11 January 2017 |deadurl = no |archiveurl = https://web.archive.org/web/20170113070447/http://www.cnbc.com/2014/03/14/buffett-blasts-bitcoin-as-mirage-stay-away.html |archivedate = 13 January 2017 |df = dmy-all }}</ref><ref name="Buffet and Dimon">{{cite news |last1=Cheng |first1=Evelyn |title=Warren Buffett and Jamie Dimon on bitcoin: Beware |url=https://www.cnbc.com/2018/06/07/warren-buffett-and-jamie-dimon-on-bitcoin-beware.html |accessdate=7 June 2018 |publisher=CNBC |date=7 June 2018}}</ref> and [[George Soros]]<ref name="GnMSoros">{{cite news |last1=Porzecanski |first1=Katia |title=George Soros: Bitcoin is a bubble, Trump is a 'danger to the world' |url=https://www.theglobeandmail.com/globe-investor/investment-ideas/george-soros-says-bitcoin-bubble-wont-have-sharp-break-like-others/article37739168/ |accessdate=7 June 2018 |agency=Bloomberg News |publisher=Globe and Mail |date=25 January 2018}}</ref> have stated similar views, as have business executives such as [[Jamie Dimon]] and [[Jack Ma]].<ref name="Yang Ma">{{cite news |last1=Yang |first1=Yingzhi |title=There’s a bitcoin bubble, says Alibaba executive chairman Jack Ma |url=http://www.scmp.com/tech/enterprises/article/2146648/theres-bitcoin-bubble-says-alibaba-executive-chairman-jack-ma |accessdate=10 June 2018 |publisher=South China Morning Post |date=18 May 2018}}</ref>

=== Energy consumption ===
Bitcoin has been criticized for the amounts of electricity consumed by mining. As of 2015, ''The Economist'' estimated that even if all miners used modern facilities, the combined electricity consumption would be 166.7 megawatts (1.46 terawatt-hours per year).<ref name=ec1305 />
At the end of 2017, the global bitcoin mining activity was estimated to consume between 1 and 4 gigawatts of electricity.<ref>{{Cite news |url = https://www.washingtonpost.com/news/energy-environment/wp/2017/12/19/why-the-bitcoin-craze-is-using-up-so-much-energy |title = Why the bitcoin craze is using up so much energy |last1 = Mooney |first1 = Chris |last2 = Mufson |first2 = Steven |date = 19 December 2017 |newspaper = The Washington Post |accessdate = 11 January 2018 |dead-url = no |df = dmy-all |quote = several experts told The Washington Post that bitcoin probably uses as much as 1 to 4 gigawatts, or billion watts, of electricity, roughly the output of one to three nuclear reactors. |archiveurl = https://web.archive.org/web/20180109212301/https://www.washingtonpost.com/news/energy-environment/wp/2017/12/19/why-the-bitcoin-craze-is-using-up-so-much-energy/ |archivedate = 9 January 2018 }}</ref> [[Politico]] noted that the banking sector today consumes about 6% of total global power, and even if bitcoin's consumption levels increased 100 fold from today's levels, bitcoin's consumption would still only amount to about 2% of global power consumption.<ref name="politico201804">{{cite news |last1 = Roberts |first1 = Paul |title = This Is What Happens When Bitcoin Miners Take Over Your Town - Eastern Washington had cheap power and tons of space. Then the suitcases of cash started arriving. |url = https://www.politico.com/magazine/story/2018/03/09/bitcoin-mining-energy-prices-smalltown-feature-217230 |accessdate = 16 March 2018 |work = Politico |date = 9 March 2018 |df = dmy-all }}</ref>

To lower the costs, bitcoin miners have set up in places like Iceland where [[geothermal energy]] is cheap and cooling [[Arctic]] air is free.{{r|dh150613}} Bitcoin miners are known to use [[hydroelectric power]] in [[Tibet]], [[Quebec]], [[Washington (state)]], and [[Austria]] to reduce electricity costs.<ref name="politico201804" /><ref name="cryptocoinnews20160914">{{cite news |last1 = Maras |first1 = Elliot |title = China’s Mining Dominance: Good Or Bad For Bitcoin? |url = https://www.cryptocoinsnews.com/chinas-mining-dominance-good-or-bad-for-bitcoin/ |accessdate = 25 November 2016 |work = Cryptocoin News |date = 14 September 2016 |deadurl = no |archiveurl = https://web.archive.org/web/20161126064550/https://www.cryptocoinsnews.com/chinas-mining-dominance-good-or-bad-for-bitcoin/ |archivedate = 26 November 2016 |df = dmy-all }}</ref><ref name="CBC20171115">{{cite news |last1 = |first1 = |title = Montreal entrepreneur banking on province's largest bitcoin 'mining' operation |url = http://www.cbc.ca/news/canada/montreal/montreal-bitcoin-mine-operation-1.4400985 |accessdate = 7 January 2018 |work = Cryptocoin News |date = 15 November 2017 |deadurl = no |archiveurl = https://web.archive.org/web/20180110191438/http://www.cbc.ca/news/canada/montreal/montreal-bitcoin-mine-operation-1.4400985 |archivedate = 10 January 2018 |df = }}</ref><ref name="verge20171221">{{cite news |last1 = Potenza |first1 = Alessandra |title = Can renewable power offset bitcoin's massive energy demands? |url = https://www.theverge.com/2017/12/21/16806772/bitcoin-cryptocurrency-energy-consumption-renewables-climate-change |accessdate = 12 January 2018 |work = TheVerge News |date = 21 December 2017 |deadurl = no |archiveurl = https://web.archive.org/web/20180112155940/https://www.theverge.com/2017/12/21/16806772/bitcoin-cryptocurrency-energy-consumption-renewables-climate-change |archivedate = 12 January 2018 |df = }}</ref> Miners are attracted to suppliers such as [[Hydro Quebec]] that have energy surpluses.<ref name="hydro2018">{{cite news |last1 = Lampert |first1 = Allison |title = Chinese bitcoin miners eye sites in energy-rich Canada |url = https://www.reuters.com/article/us-canada-bitcoin-china/chinese-bitcoin-miners-eye-sites-in-energy-rich-canada-idUSKBN1F10BU |accessdate = 14 January 2018 |work = Reuters |date = 12 January 2018 |deadurl = no |archiveurl = https://web.archive.org/web/20180114001018/https://www.reuters.com/article/us-canada-bitcoin-china/chinese-bitcoin-miners-eye-sites-in-energy-rich-canada-idUSKBN1F10BU |archivedate = 14 January 2018 |df = }}</ref> According to a [[University of Cambridge]] study, much of bitcoin mining is done in China, where electricity is subsidized by the government.<ref>{{cite news|title=Bitcoin is literally ruining the earth, claim experts|url=https://www.independent.co.uk/life-style/gadgets-and-tech/news/bitcoin-environment-green-energy-power-global-warming-climate-change-a8094661.html|accessdate=23 January 2018|work=The Independent|date=6 December 2017|deadurl=no|archiveurl=https://web.archive.org/web/20180119145633/http://www.independent.co.uk/life-style/gadgets-and-tech/news/bitcoin-environment-green-energy-power-global-warming-climate-change-a8094661.html|archivedate=19 January 2018}}</ref><ref>{{cite news|title=The Hard Math Behind Bitcoin's Global Warming Problem|url=https://www.wired.com/story/bitcoin-global-warming/|accessdate=23 January 2018|work=WIRED|date=15 December 2017|deadurl=no|archiveurl=https://web.archive.org/web/20180121095259/https://www.wired.com/story/bitcoin-global-warming/|archivedate=21 January 2018}}</ref>

=== Price manipulation investigation ===
An official investigation into bitcoin traders was reported in May 2018.<ref name="Times05252018">{{cite news|last1=Dean|first1=James|title=Bitcoin investigation to focus on British traders, US officials examine manipulation of cryptocurrency prices|url=https://www.thetimes.co.uk/article/bitcoin-investigation-to-focus-on-british-traders-c58brwn60|accessdate=25 May 2018|publisher=The Times|date=25 May 2018}}</ref> The U.S. Justice Department launched an investigation into possible price manipulation, including the techniques of [[spoofing (finance)|spoofing]] and [[wash trade]]s.<ref name="chloeFT">{{cite news|last1=Cornish|first1=Chloe|title=Bitcoin slips again on reports of US DoJ investigation|url=https://www.ft.com/content/5d8f06f2-5f3a-11e8-9334-2218e7146b04|accessdate=24 May 2018|publisher=Financial Times|date=24 May 2018}}</ref><ref name="Bloom052418">{{cite news|last1=Robinson|first1=Matt|last2=Schoenberg|first2=Tom|title=U.S. Launches Criminal Probe into Bitcoin Price Manipulation|url=https://www.bloomberg.com/news/articles/2018-05-24/bitcoin-manipulation-is-said-to-be-focus-of-u-s-criminal-probe|accessdate=24 May 2018|publisher=Bloomberg|date=24 May 2018}}</ref><ref name="USAT05242018">{{cite news|last1=McCoy|first1=Kevin|title=Bitcoin value gyrates amid report of Department of Justice manipulation investigation|url=https://www.usatoday.com/story/money/2018/05/24/bitcoin-value-gyrates-after-report-department-justice-probe/640289002/|accessdate=25 May 2018|publisher=[[USA Today]]|date=24 May 2018}}</ref> Traders in the U.S., the U.K, South Korea, and possibly other countries are being investigated.<ref name="Times05252018"/> Brett Redfearn, head of the [[U.S. Securities and Exchange Commission]]'s Division of Trading and Markets, had identified several manipulation techniques of concern in March 2018.

The U.S. federal investigation was prompted by concerns of possible manipulation during futures settlement dates. The final settlement price of CME bitcoin futures is determined by prices on four exchanges, [[Bitstamp]], [[Coinbase]], [[Paxos (company)|itBit]] and [[Kraken (bitcoin exchange)|Kraken]]. Following the first delivery date in January 2018, the CME requested extensive detailed trading information but several of the exchanges refused to provide it and later provided only limited data. The [[Commodity Futures Trading Commission]] then subpoenaed the data from the exchanges.<ref name="MWmanipulation">{{cite news |last1=Rubin |first1=Gabriel T. |last2=Michaels |first2=Dave |last3=Osipovich |first3=Alexander |title=U.S. regulators demand trading data from bitcoin exchanges in manipulation probe |url=https://www.marketwatch.com/story/us-regulators-demand-trading-data-from-bitcoin-exchanges-in-manipulation-probe-2018-06-08 |accessdate=9 June 2018 |publisher=MarketWatch |date=8 June 2018}} Note:this is a short open access version of a Wall Street Journal article</ref><ref name="WSJmanipulation">{{cite news |last1=Rubin |first1=Gabriel T. |last2=Michaels |first2=Dave |last3=Osipovich |first3=Alexander |title=U.S. regulators demand trading data from bitcoin exchanges in manipulation probe |url=https://www.wsj.com/articles/u-s-regulators-demand-trading-data-from-bitcoin-exchanges-in-manipulation-probe-1528492835 |accessdate=9 June 2018 |publisher=Wall Street Journal |date=8 June 2018}} (paywalled)</ref>

State and provincial securities regulators, coordinated through the [[North American Securities Administrators Association]], are investigating "bitcoin scams" and [[Initial coin offering|ICOs]] in 40 jurisdictions.<ref name="WaPo52118">{{cite news|last1=Fung|first1=Brian|title=State regulators unveil nationwide crackdown on suspicious cryptocurrency investment schemes|url=https://www.washingtonpost.com/news/the-switch/wp/2018/05/21/state-regulators-unveil-nationwide-crackdown-on-suspicious-cryptocurrency-investment-schemes/|accessdate=27 May 2018|publisher=Washington Post|date=21 May 2018}}</ref> Academic research published in the [[Journal of Monetary Economics]] concluded that price manipulation occurred during the [[Mt Gox]] bitcoin theft and that the market remains vulnerable to manipulation.<ref name="JME">{{cite journal|last1=Gandal|first1=Neil|last2=Hamrick|first2=J.T.|last3=Moore|first3=Tyler|last4=Oberman|first4=Tali|title=Price manipulation in the Bitcoin ecosystem|journal=[[Journal of Monetary Economics]]|date=May 2018|volume=95|page=86-96|url=https://www.sciencedirect.com/science/article/pii/S0304393217301666|accessdate=25 May 2018}}</ref> The history of hacks, fraud and theft involving bitcoin dates back to at least 2011.<ref>{{cite web|last1=Lee|first1=Tim|title=A brief history of Bitcoin hacks and frauds|url=https://arstechnica.com/tech-policy/2017/12/a-brief-history-of-bitcoin-hacks-and-frauds/|website=Ars Technica|accessdate=27 May 2018|date=12 December 2017}}</ref>

Research by John M. Griffin and Amin Shams in 2018 suggests that trading associated with increases in the amount of the [[Tether (cryptocurrency)|Tether cryptocurrency]] and associated trading at the [[Bitfinex]] exchange account for about half of the price increase in bitcoin in late 2017.<ref name="untethered">{{cite journal |last1=Griffin |first1=John M. |last2=Shams |first2=Amin |title=Is Bitcoin Really Un-Tethered? |journal=Social Sciences Research Network |date=13 June 2018 |url=https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3195066 |accessdate=13 June 2018}}</ref><ref name="Artynyt">{{cite news |last1=Popper |first1=Nathaniel |title=Bitcoin’s Price Was Artificially Inflated Last Year, Researchers Say |url=https://www.nytimes.com/2018/06/13/technology/bitcoin-price-manipulation.html |accessdate=13 June 2018 |publisher=New York Times |date=13 June 2018}}</ref>

JL van der Velde, CEO of both Bitfinex and Tether, denied the claims of price manipulation: "Bitfinex nor Tether is, or has ever, engaged in any sort of market or price manipulation. Tether issuances cannot be used to prop up the price of bitcoin or any other coin/token on Bitfinex."<ref name="WaPoVdV">{{cite news |last1=Shaban |first1=Hamza |title=Bitcoin’s astronomical rise last year was buoyed by market manipulation, researchers say |url=https://www.washingtonpost.com/news/the-switch/wp/2018/06/14/bitcoins-astronomical-rise-last-year-was-buoyed-by-market-manipulation-researchers-say/ |accessdate=14 June 2018 |publisher=Washington Post |date=14 June 2018}}</ref>

=== Ponzi scheme and pyramid scheme concerns ===

Various journalists,<ref name="dh150613" /><ref>{{cite news |last1 = Braue |first1 = David |title = Bitcoin confidence game is a Ponzi scheme for the 21st century |url = http://www.zdnet.com/article/bitcoin-confidence-game-is-a-ponzi-scheme-for-the-21st-century/ |accessdate = 5 October 2016 |publisher = ZDNet |date = 11 March 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20161006050933/http://www.zdnet.com/article/bitcoin-confidence-game-is-a-ponzi-scheme-for-the-21st-century/ |archivedate = 6 October 2016 |df = dmy-all }}</ref> economists,<ref>{{cite web |url = https://www.cnbc.com/id/101479123 |title = Roubini launches stinging attack on bitcoin |publisher = [[CNBC]] |date = 10 March 2014 |accessdate = 2 July 2014 |author = Clinch, Matt |deadurl = no |archiveurl = https://web.archive.org/web/20141006074352/http://www.cnbc.com/id/101479123 |archivedate = 6 October 2014 |df = dmy-all }}</ref><ref name="dd">{{cite web |url = http://www.dailydot.com/opinion/why-bitcoin-ponzi-scheme/ |title = Bitcoins: The second biggest Ponzi scheme in history |publisher = The Daily Dot |date = 3 December 2013 |accessdate = 23 May 2016 |author = North, Gary |author-link = Gary North (economist) |deadurl = no |archiveurl = https://web.archive.org/web/20160617002042/http://www.dailydot.com/opinion/why-bitcoin-ponzi-scheme/ |archivedate = 17 June 2016 |df = dmy-all }}</ref> and the central bank of Estonia<ref name="Ott Ummelas and Milda Seputyte">{{cite news |url = https://www.bloomberg.com/news/2014-01-30/bitcoin-ponzi-scheme-worry-sparks-estonia-central-bank-caution.html |title = Bitcoin ‘Ponzi’ Concern Sparks Warning From Estonia Bank |publisher = Bloomberg |work = bloomberg.com |date = 31 January 2014 |accessdate = 1 April 2014 |author1 = Ott Ummelas |author2 = Milda Seputyte |lastauthoramp = yes |deadurl = no |archiveurl = https://web.archive.org/web/20140329214501/http://www.bloomberg.com/news/2014-01-30/bitcoin-ponzi-scheme-worry-sparks-estonia-central-bank-caution.html |archivedate = 29 March 2014 |df = dmy-all }}</ref> have voiced concerns that bitcoin is a [[Ponzi scheme]]. In 2013, [[Eric Posner]], a law professor at the University of Chicago, stated that "a real Ponzi scheme takes fraud; bitcoin, by contrast, seems more like a collective delusion."<ref name="Posner, Eric">{{cite web |url = http://www.slate.com/articles/news_and_politics/view_from_chicago/2013/04/bitcoin_is_a_ponzi_scheme_the_internet_currency_will_collapse.html |title = Bitcoin is a Ponzi scheme—the Internet's favorite currency will collapse. |work = Slate |date = 11 April 2013 |accessdate = 1 April 2014 |author = Posner, Eric |authorlink = Eric Posner |deadurl = no |archiveurl = https://web.archive.org/web/20140326185128/http://www.slate.com/articles/news_and_politics/view_from_chicago/2013/04/bitcoin_is_a_ponzi_scheme_the_internet_currency_will_collapse.html |archivedate = 26 March 2014 |df = dmy-all }}</ref> A 2014 report by the [[World Bank]] concluded that bitcoin was not a deliberate Ponzi scheme.<ref>{{cite web |title = Ponzis: The Science and Mystique of a Class of Financial Frauds |url = http://www-wds.worldbank.org/external/default/WDSContentServer/WDSP/IB/2014/07/16/000112742_20140716115536/Rendered/PDF/WPS6967.pdf |author = Kaushik Basu |publisher = [[World Bank Group]] |date = July 2014 |accessdate = 30 October 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20141031043236/http://www-wds.worldbank.org/external/default/WDSContentServer/WDSP/IB/2014/07/16/000112742_20140716115536/Rendered/PDF/WPS6967.pdf |archivedate = 31 October 2014 |df = dmy-all }}</ref>{{rp|7}} The Swiss [[Federal Council (Switzerland)|Federal Council]]<ref name="FC20140625">{{cite web |publisher = [[Swiss Confederation]] |title = Federal Council report on virtual currencies in response to the Schwaab (13.3687) and Weibel (13.4070) postulates |work = [[Federal Council (Switzerland)]] |date = 25 June 2014 |accessdate = 28 November 2014 |url = http://www.news.admin.ch/NSBSubscriber/message/attachments/35355.pdf |deadurl = no |archiveurl = https://web.archive.org/web/20141205182453/http://www.news.admin.ch/NSBSubscriber/message/attachments/35355.pdf |archivedate = 5 December 2014 |df = dmy-all }}</ref>{{rp|21}} examined the concerns that bitcoin might be a pyramid scheme; it concluded that "Since in the case of bitcoin the typical promises of profits are lacking, it cannot be assumed that bitcoin is a pyramid scheme." In July 2017, billionaire [[Howard Marks (investor)|Howard Marks]] referred to bitcoin as a [[pyramid scheme]].<ref>{{cite web |title = This Billionaire Just Called Bitcoin a 'Pyramid Scheme' |url = http://fortune.com/2017/07/27/howard-marks-bitcoin-pyramid-scheme/ |accessdate = 23 September 2017 |deadurl = no |archiveurl = https://web.archive.org/web/20170924045918/http://fortune.com/2017/07/27/howard-marks-bitcoin-pyramid-scheme/ |archivedate = 24 September 2017 |df = dmy-all }}</ref>

On 12 September 2017, [[Jamie Dimon]], CEO of [[JP Morgan Chase]], called bitcoin a "fraud" and said he would fire anyone in his firm caught trading it. [[Zero Hedge]] claimed that the same day Dimon made his statement, JP Morgan also purchased a large amount of bitcoins for its clients.<ref>{{cite web |title = JPMorgan Helps Clients Buy Bitcoin Despite CEO Calling Bitcoin ‘a Fraud’ |url = http://fortune.com/2017/09/18/jpmorgan-buy-bitcoin-ceo-callingfraud/ |accessdate = 23 September 2017 |deadurl = no |archiveurl = https://web.archive.org/web/20170923172754/http://fortune.com/2017/09/18/jpmorgan-buy-bitcoin-ceo-callingfraud/ |archivedate = 23 September 2017 |df = dmy-all }}</ref> In a January 2018 interview Dimon voiced regrets about his earlier remarks, and said "The blockchain is real. You can have cryptodollars in yen and stuff like that. [[Initial coin offering|ICO]]s ... you got to look at every one individually."<ref>{{cite web|work=CNBC|title=Jamie Dimon says he regrets calling bitcoin a fraud and believes in the technology behind it|url=https://www.cnbc.com/2018/01/09/jamie-dimon-says-he-regrets-calling-bitcoin-a-fraud.html|date=9 January 2018|deadurl=no|archiveurl=https://web.archive.org/web/20180113085325/https://www.cnbc.com/2018/01/09/jamie-dimon-says-he-regrets-calling-bitcoin-a-fraud.html|archivedate=13 January 2018}}</ref>

=== Alleged criminal activity ===
{{See also|Bitcoin network#Alleged criminal activity}}

The use of bitcoin by criminals has attracted the attention of financial regulators, legislative bodies, law enforcement, and the media.<ref name="Lavin, Tim">{{cite news |url = http://www.bloombergview.com/articles/2013-08-08/did-the-sec-just-validate-bitcoin-no- |title = The SEC Shows Why Bitcoin Is Doomed |publisher = Bloomberg LP |work = bloomberg.com |date = 8 August 2013 |accessdate = 20 October 2013 |author = Lavin, Tim |deadurl = no |archiveurl = https://web.archive.org/web/20140325214514/http://www.bloombergview.com/articles/2013-08-08/did-the-sec-just-validate-bitcoin-no- |archivedate = 25 March 2014 |df = dmy-all }}</ref> In the United States, the [[Federal Bureau of Investigation|FBI]] prepared an intelligence assessment,<ref name="fbi_report">{{cite news |url = https://www.wired.com/images_blogs/threatlevel/2012/05/Bitcoin-FBI.pdf |title = Bitcoins Virtual Currency: Unique Features Present Challenges for Deterring Illicit Activity |publisher = FBI |work = Cyber Intelligence Section and Criminal Intelligence Section |date = 24 April 2012 |accessdate = 2 November 2014 |deadurl = no |archiveurl = https://web.archive.org/web/20141014180733/http://www.wired.com/images_blogs/threatlevel/2012/05/Bitcoin-FBI.pdf |archivedate = 14 October 2014 |df = dmy-all }}</ref> the [[U.S. Securities and Exchange Commission|SEC]] issued a pointed warning about investment schemes using virtual currencies,<ref name="Lavin, Tim" /> and the [[U.S. Senate]] held a hearing on virtual currencies in November 2013.<ref name="USoff" />

Several news outlets have asserted that the popularity of bitcoins hinges on the ability to use them to purchase illegal goods.<ref name=Monetarists>{{cite news |url = http://www.economist.com/node/21563752 |title = Monetarists Anonymous |publisher = The Economist Newspaper Limited |work = The Economist |date = 29 September 2012 |accessdate = 21 October 2013 |deadurl = no |archiveurl = https://web.archive.org/web/20131020192331/http://www.economist.com/node/21563752 |archivedate = 20 October 2013 |df = dmy-all }}</ref><ref>{{cite web |url = https://www.theguardian.com/world/2013/mar/22/silk-road-online-drug-marketplace |title = Silk Road: the online drug marketplace that officials seem powerless to stop |publisher = Guardian News and Media Limited |work = theguardian.com |date = 22 March 2013 |accessdate = 20 October 2013 |author = Ball, James |deadurl = no |archiveurl = https://web.archive.org/web/20131012012106/http://www.theguardian.com/world/2013/mar/22/silk-road-online-drug-marketplace |archivedate = 12 October 2013 |df = dmy-all }}</ref> In 2014, researchers at the [[University of Kentucky]] found "robust evidence that computer programming enthusiasts and illegal activity drive interest in bitcoin, and find limited or no support for political and investment motives".<ref name=uok>{{cite journal |ssrn = 2518603 |title = Characteristics of Bitcoin Users: An Analysis of Google Search Data |author1 = Matthew Graham Wilson |author2 = Aaron Yelowitz |lastauthoramp = yes |journal = Social Science Research Network |date = November 2014 |volume = Working Papers Series }}</ref>

Australian researchers have estimated that 25% of all bitcoin users and 44% of all bitcoin transactions are associated with illegal activity as of April 2017. There were an estimated 24 million bitcoin users primarily using bitcoin for illegal activity, who held $8 billion worth of bitcoin, and made 36 million transactions valued at $72 billion.<ref name="SDB1">{{cite news |last1=Foley |first1=Sean |last2=Karlsen |first2=Jonathan R. |last3=Putniņš |first3=Tālis J. |title=Sex, drugs, and bitcoin: How much illegal activity is financed through cryptocurrencies? |url=https://www.law.ox.ac.uk/business-law-blog/blog/2018/02/sex-drugs-and-bitcoin-how-much-illegal-activity-financed-through |accessdate=11 June 2018 |agency=Oxford Business Law Blog |publisher=University of Oxford Faculty of Law |date=19 February 2018}}</ref><ref name="SDB2">{{cite journal |last1=Foley |first1=Sean |last2=Karlsen |first2=Jonathan R. |last3=Putniņš |first3=Tālis J. |title=Sex, Drugs, and Bitcoin: How Much Illegal Activity Is Financed Through Cryptocurrencies? |journal=Social Science Research Network |date=30 January 2018 |url=https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3102645 |accessdate=11 June 2018}}</ref>

Major thefts involving bitcoin 2012 - 2017, according to Bloomberg include<ref name="HackList">{{cite news |last1=Tan |first1=Andrea |last2=Nakamura |first2=Yuji |url=https://www.insurancejournal.com/news/international/2018/02/01/479206.htm |title=Timeline: Growing List of Major Cryptocurrency Heists |accessdate=2 July 2018 |agency=Bloomberg |publisher=Insurance Journal |date=1 February 2018}}</ref>
*December 2017, [[NiceHash]], a marketplace for crypto-mining reported $63 million worth of bitcoin stolen
*November 2017, $31 million worth of [[Tether (cryptocurrency)|tether tokens]] reported stolen and converted to bitcoins
*April 2017, 4,000 bitcoins stolen from the YouBit exchange in April<ref name="YouBit">{{cite news |last1=Partington |first1=Richard |title=Bitcoin not a threat to financial stability, say European economists |url=https://www.theguardian.com/technology/2017/dec/19/korean-cryptocurrency-exchange-close-second-hacking-youbit |accessdate=2 July 2018 |publisher=Guardian |date=19 December 2017}}</ref>
*August 2016, about $65 million worth of bitcoin stolen in the [[Bitfinex hack]]
*May 2016, $2 million worth of bitcoin and [[ether]] stolen from the [[Gatecoin]] exchange
*January 2015, $5 million worth of bitcoin stolen from the [[Bitstamp]] exchange
*February 2014, the [[Mt. Gox]] exchange reports $480 million worth of bitcoin missing
*September 2012, the BitFloor exchange reported about $250,000 worth of bitcoin stolen.

===Advertising bans===
Bitcoin and other cryptocurrency advertisements are banned on [[Facebook]],<ref name="wiredface">{{cite news|last1=Matsakis|first1=Louise|title=Cryptocurrency scams are just straight-up trolling at this point|url=https://www.wired.com/story/cryptocurrency-scams-ico-trolling/|accessdate=2 April 2018|publisher=[[Wired (magazine)|Wired]]|date=30 January 2018}}</ref> [[Google]], [[Twitter]],<ref name="ToISW">{{cite news|last1=Weinglass|first1=Simona|title=European Union bans binary options, strictly regulates CFDs|url=https://www.timesofisrael.com/european-union-bans-binary-options-strictly-regulates-cfds/|accessdate=2 April 2018|publisher=[[Times of Israel]]|date=28 March 2018}}</ref> [[Bing (search engine)|Bing]],<ref name="bing51418">{{cite web|last1=Alsoszatai-Petheo|first1=Melissa|title=Bing Ads to disallow cryptocurrency advertising|url=https://advertise.bingads.microsoft.com/en-us/blog/post/may-2018/bing-ads-to-disallow-cryptocurrency-advertising?feed=blogposts|publisher=Microsoft|accessdate=16 May 2018|date=14 May 2018}}</ref> [[Snapchat]], [[LinkedIn]] and [[MailChimp]].<ref name="3key">{{cite news|last1=French|first1=Jordan|title=3 Key Factors Behind Bitcoin's Current Slide|url=https://www.thestreet.com/story/14541510/1/whats-behind-bitcoin-price-slump.html|accessdate=2 April 2018|publisher=theStreet.com|date=2 April 2018|ref=`}}</ref> Chinese internet platforms [[Baidu]], [[Tencent]], and [[Weibo (company)|Weibo]] have also prohibited bitcoin advertisements. The Japanese platform [[Line Corporation|Line]] and the Russian platform [[Yandex]] have similar prohibitions.<ref>{{cite news|last1=Wilson|first1=Thomas|title=Twitter and LinkedIn ban cryptocurrency adverts – leaving regulators behind|url=https://www.independent.co.uk/news/business/analysis-and-features/twitter-ban-cryptocurrency-adverts-regulators-bitcoin-facebook-social-media-a8277176.html|accessdate=3 April 2018|agency=[[Reuters]]|publisher=Independent|date=28 March 2018}}</ref>

== Documentation ==

=== Academia ===

In September 2015, the establishment of the [[peer-reviewed]] [[academic journal]] ''[[Ledger (journal)|Ledger]]'' ({{ISSN|2379-5980}}) was announced. It will cover studies of cryptocurrencies and related technologies, and is published by the [[University of Pittsburgh]].<ref>{{cite web |url = http://motherboard.vice.com/read/introducing-ledger-the-first-bitcoin-only-academic-journal |title = Introducing Ledger, the First Bitcoin-Only Academic Journal |author = |date = |work = Motherboard |deadurl = no |archiveurl = https://web.archive.org/web/20170110172807/http://motherboard.vice.com/read/introducing-ledger-the-first-bitcoin-only-academic-journal |archivedate = 10 January 2017 |df = dmy-all }}</ref>

The journal encourages authors to [[Digital signature|digitally sign]] a [[Hash function|file hash]] of submitted papers, which will then be [[Trusted timestamping|timestamped]] into the bitcoin [[blockchain]]. Authors are also asked to include a personal bitcoin address in the first page of their papers.<ref>{{cite web |url = http://ledgerjournal.org/ojs/index.php/ledger/about/editorialPolicies#custom-0 |title = Editorial Policies |author = |date = |work = ledgerjournal.org |deadurl = no |archiveurl = https://web.archive.org/web/20161223135741/http://www.ledgerjournal.org/ojs/index.php/ledger/about/editorialPolicies#custom-0 |archivedate = 23 December 2016 |df = dmy-all }}</ref><ref>{{Cite journal |last = |first = |date = 2015 |title = How to Write and Format an Article for Ledger |url = http://ledger.pitt.edu/ojs/public/journals/1/AuthorGuide.pdf |journal = [[Ledger (journal)|Ledger]] |volume = |issue = |doi = 10.5195/LEDGER.2015.1 |pmid = |accessdate = |via = |deadurl = no |archiveurl = https://web.archive.org/web/20150922190603/http://ledger.pitt.edu/ojs/public/journals/1/AuthorGuide.pdf |archivedate = 22 September 2015 |doi-broken-date = 18 March 2018}}</ref>

=== Film ===

The documentary film, ''[[The Rise and Rise of Bitcoin]]'' (late 2014), features interviews with people who use bitcoin, such as a computer programmer and a drug dealer.<ref>{{cite news |url = https://www.nytimes.com/2014/10/03/movies/the-rise-and-rise-of-bitcoin-from-nicholas-mross.html?_r=0 |title = Financial Wild West |newspaper = The New York Times |date = 2 October 2014 |accessdate = 8 May 2015 |author = Kenigsberg, Ben |deadurl = no |archiveurl = https://web.archive.org/web/20150518232516/http://www.nytimes.com/2014/10/03/movies/the-rise-and-rise-of-bitcoin-from-nicholas-mross.html?_r=0 |archivedate = 18 May 2015 |df = dmy-all }}</ref>

== See also ==

{{Wikipedia books}}

{{Div col}}
* [[Alternative currency]]
* [[Alternative currency]]
* [[List of cryptocurrencies]]
* [[Base58]]
* [[Crypto-anarchism]]
* [[List of bitcoin companies]]
* [[List of bitcoin organizations]]
* [[List of SHA-256 crypto currencies|SHA-256 crypto currencies]]
* [[Virtual currency law in the United States]]
{{Div col end}}

{{Portal bar|Cryptography|Business and economics|Free and open-source software|Internet|Numismatics}}

== Notes ==

{{Notelist|30em}}

== References ==


==Notes==
{{Reflist|30em}}
{{Notelist}}


==References==
== External links ==
{{Reflist}}
* [https://www.bitcoin.org/ Bitcoin.org website]


== Further reading ==
{{Commons category|Bitcoin}}
* {{cite web |last=Nakamoto |first=Satoshi |date=31 October 2008 |title=Bitcoin: A Peer-to-Peer Electronic Cash System |url=https://bitcoin.org/bitcoin.pdf |url-status=dead |archive-url=https://web.archive.org/web/20140320135003/https://bitcoin.org/bitcoin.pdf |archive-date=20 March 2014 |access-date=28 April 2014 |publisher=bitcoin.org}}


{{Bitcoin}}
{{Bitcoin}}
{{Cryptocurrencies}}
{{Cryptocurrencies}}
{{Currency symbols}}
{{Authority control}}
{{Authority control}}
{{Subject bar|commons=Bitcoin|portal1=Business and economics|portal2=Free and open-source software|portal3=Internet|portal4=Numismatics|portal5=Money}}


[[Category:Alternative currencies]]
[[Category:Bitcoin| ]]
[[Category:Bitcoin| ]]
[[Category:2009 software]]
[[Category:Application layer protocols]]
[[Category:Computer-related introductions in 2009]]
[[Category:Cryptocurrencies]]
[[Category:Digital currencies| ]]
[[Category:Currency introduced in 2009]]

Latest revision as of 17:03, 17 June 2024

Bitcoin
Prevailing bitcoin logo
Logo
Denominations
PluralBitcoins
Symbol
(Unicode: U+20BF BITCOIN SIGN)[1]
CodeBTC
Precision10−8
Subunits
11000Millibitcoin
11000000Microbitcoin
1100000000Satoshi[a][2]
Development
Original author(s)Satoshi Nakamoto
White paper"Bitcoin: A Peer-to-Peer Electronic Cash System"
Implementation(s)Bitcoin Core
Initial release0.1.0 / 9 January 2009 (15 years ago) (2009-01-09)
Latest release27.1 / 17 June 2024 (9 days ago) (2024-06-17)[3]
Code repositorygithub.com/bitcoin/bitcoin
Development statusActive
Written inC++
Source modelFree and open-source software
LicenseMIT License
Ledger
Ledger start3 January 2009 (15 years ago) (2009-01-03)
Timestamping schemeProof of work (partial hash inversion)
Hash functionSHA-256 (two rounds)
Issuance scheduleDecentralized (block reward)
Initially ₿50 per block, halved every 210,000 blocks
Block reward₿3.125 (as of 2024)
Block time10 minutes
Circulating supply₿19,591,231 (as of 6 January 2024)
Supply limit₿21,000,000[b]
Valuation
Exchange rateFloating
Demographics
Official user(s)El Salvador[4]

Bitcoin (abbreviation: BTC; sign: ) is the first decentralized cryptocurrency. Nodes in the peer-to-peer bitcoin network verify transactions through cryptography and record them in a public distributed ledger, called a blockchain, without central oversight. Consensus between nodes is achieved using a computationally intensive process based on proof of work, called mining, that guarantees the security of the bitcoin blockchain. Mining consumes increasing quantities of electricity and has been criticized for its environmental effects.[5]

Based on a free market ideology, bitcoin was invented in 2008 by Satoshi Nakamoto, an unknown person.[6] Use of bitcoin as a currency began in 2009,[7] with the release of its open-source implementation.[8]: ch. 1  In 2021, El Salvador adopted it as legal tender.[4] Bitcoin is currently used more as a store of value and less as a medium of exchange or unit of account. It is mostly seen as an investment and has been described by many scholars as an economic bubble.[9] As bitcoin is pseudonymous, its use by criminals has attracted the attention of regulators, leading to its ban by several countries as of 2021.[10]

History

Background

Before bitcoin, several digital cash technologies were released, starting with David Chaum's ecash in the 1980s.[11] The idea that solutions to computational puzzles could have some value was first proposed by cryptographers Cynthia Dwork and Moni Naor in 1992.[11] The concept was independently rediscovered by Adam Back who developed Hashcash, a proof-of-work scheme for spam control in 1997.[11] The first proposals for distributed digital scarcity-based cryptocurrencies came from cypherpunks Wei Dai (b-money) and Nick Szabo (bit gold) in 1998.[12] In 2004, Hal Finney developed the first currency based on reusable proof of work.[13] These various attempts were not successful:[11] Chaum's concept required centralized control and no banks wanted to sign on, Hashcash had no protection against double-spending, while b-money and bit gold were not resistant to Sybil attacks.[11]

2008–2009: Creation

External image
image icon Cover page of The Times 3 January 2009 showing the headline used in the genesis block
Bitcoin logos made by Satoshi Nakamoto in 2009 (left) and 2010 (right) depict bitcoins as gold tokens.

The domain name bitcoin.org was registered on 18 August 2008.[14] On 31 October 2008, a link to a white paper authored by Satoshi Nakamoto titled Bitcoin: A Peer-to-Peer Electronic Cash System was posted to a cryptography mailing list.[15] Nakamoto implemented the bitcoin software as open-source code and released it in January 2009.[7] Nakamoto's identity remains unknown.[6] All individual components of bitcoin originated in earlier academic literature.[11] Nakamoto's innovation was their complex interplay resulting in the first decentralized, Sybil resistant, Byzantine fault tolerant digital cash system, that would eventually be referred to as the first blockchain.[11][16] Nakamoto's paper was not peer reviewed and was initially ignored by academics, who argued that it could not work.[11]

On 3 January 2009, the bitcoin network was created when Nakamoto mined the starting block of the chain, known as the genesis block.[17] Embedded in this block was the text "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks", which is the date and headline of an issue of The Times newspaper.[7] Nine days later, Hal Finney received the first bitcoin transaction: ten bitcoins from Nakamoto.[18] Wei Dai and Nick Szabo were also early supporters.[17] On May 22, 2010, the first known commercial transaction using bitcoin occurred when programmer Laszlo Hanyecz bought two Papa John's pizzas for ₿10,000, in what would later be celebrated as "Bitcoin Pizza Day".[19]

2010–2012: Early growth

Blockchain analysts estimate that Nakamoto had mined about one million bitcoins[20] before disappearing in 2010 when he handed the network alert key and control of the code repository over to Gavin Andresen. Andresen later became lead developer at the Bitcoin Foundation,[21][22] an organization founded in September 2012 to promote bitcoin.[23]

After early "proof-of-concept" transactions, the first major users of bitcoin were black markets, such as the dark web Silk Road. During its 30 months of existence, beginning in February 2011, Silk Road exclusively accepted bitcoins as payment, transacting ₿9.9 million, worth about $214 million.[24]: 222 

2013–2014: First regulatory actions

In March 2013, the US Financial Crimes Enforcement Network (FinCEN) established regulatory guidelines for "decentralized virtual currencies" such as bitcoin, classifying American bitcoin miners who sell their generated bitcoins as money services businesses, subject to registration and other legal obligations.[25] In May 2013, US authorities seized the unregistered exchange Mt. Gox.[26] In June 2013, the US Drug Enforcement Administration seized ₿11.02 from a man attempting to use them to buy illegal substances. This marked the first time a government agency had seized bitcoins.[27] The FBI seized about ₿30,000 in October 2013 from Silk Road, following the arrest of its founder Ross Ulbricht.[28]

In December 2013, the People's Bank of China prohibited Chinese financial institutions from using bitcoin.[29] After the announcement, the value of bitcoin dropped,[30] and Baidu no longer accepted bitcoins for certain services.[31] Buying real-world goods with any virtual currency had been illegal in China since at least 2009.[32]

2015–2019

Research produced by the University of Cambridge estimated that in 2017, there were 2.9 to 5.8 million unique users using a cryptocurrency wallet, most of them using bitcoin.[33] In August 2017, the SegWit software upgrade was activated. Segwit was intended to support the Lightning Network as well as improve scalability.[34] SegWit opponents, who supported larger blocks as a scalability solution, forked to create Bitcoin Cash, one of many forks of bitcoin.[35]

In December 2017, the first futures on bitcoin was introduced by the Chicago Mercantile Exchange (CME).[36]

In February 2018, the price crashed after China imposed a complete ban on Bitcoin trading.[37] The percentage of bitcoin trading in the Chinese renminbi fell from over 90% in September 2017 to less than 1% in June 2018.[38] During the same year, Bitcoin prices were negatively affected by several hacks or thefts from cryptocurrency exchanges.[39]

2020–present

Bitcoin price in US dollars

In 2020, some major companies and institutions started to acquire bitcoin: MicroStrategy invested $250 million in bitcoin as a treasury reserve asset,[40] Square, Inc., $50 million,[41] and MassMutual, $100 million.[42] In November 2020, PayPal added support for bitcoin in the US.[43]

In February 2021, Bitcoin's market capitalization reached $1 trillion for the first time.[44] In November 2021, the Taproot soft-fork upgrade was activated, adding support for Schnorr signatures, improved functionality of smart contracts and Lightning Network.[45] Before, Bitcoin only used a custom elliptic curve with the ECDSA algorithm to produce signatures.[46]: 101  In September 2021, Bitcoin became legal tender in El Salvador, alongside the US dollar.[4] In October 2021, the first bitcoin futures Exchange-traded fund (ETF), called BITO, from ProShares was approved by the SEC and listed on the CME.[47]

In May and June 2022, the bitcoin price fell following the collapses of TerraUSD, a stablecoin,[48] and the Celsius Network, a cryptocurrency loan company.[49][50]

In 2023, ordinals—non-fungible tokens (NFTs)—on Bitcoin, went live.[51] In January 2024, the first 11 US spot bitcoin ETFs began trading, offering direct exposure to bitcoin for the first time on American stock exchanges.[52][53] As of June 2023 River Financial estimated that Bitcoin had 81.7 million users, about 1% of the global population.[54]

Design

Units and divisibility

The unit of account of the bitcoin system is the bitcoin. It is most commonly represented with the symbol[1] and the currency code BTC. However, the BTC code does not conform to ISO 4217 as BT is the country code of Bhutan,[55] and ISO 4217 requires the first letter used in global commodities to be 'X'.[55] XBT, a code that conforms to ISO 4217 though not officially part of it,[55] is used by Bloomberg L.P.[56]

No uniform capitalization convention exists; some sources use Bitcoin, capitalized, to refer to the technology and network, and bitcoin, lowercase, for the unit of account.[57] The Cambridge Advanced Learner's Dictionary and the Oxford Advanced Learner's Dictionary use the capitalized and lowercase variants without distinction.[58][59]

One bitcoin is divisible to eight decimal places.[8]: ch. 5  Units for smaller amounts of bitcoin are the millibitcoin (mBTC), equal to 11000 bitcoin, and the satoshi[a] (sat), representing 1100000000 (one hundred millionth) bitcoin, the smallest amount possible.[2] 100,000 satoshis are one mBTC.[60]

Blockchain

As a decentralized system, bitcoin operates without a central authority or single administrator,[61] so that anyone can create a new bitcoin address and transact without needing any approval.[8]: ch. 1  This is accomplished through a specialized distributed ledger called a blockchain that records bitcoin transactions.[62]

The blockchain is implemented as an ordered list of blocks. Each block contains a SHA-256 hash of the previous block,[62] chaining them in chronological order.[8]: ch. 7 [62] The blockchain is maintained by a peer-to-peer network.[24]: 215–219  Individual blocks, public addresses, and transactions within blocks are public information, and can be examined using a blockchain explorer.[63]

Nodes validate and broadcast transactions, each maintaining a copy of the blockchain for ownership verification.[64] A new block is created every 10 minutes on average, updating the blockchain across all nodes without central oversight. This process tracks bitcoin spending, ensuring each bitcoin is spent only once. Unlike a traditional ledger that tracks physical currency, bitcoins exist digitally as unspent outputs of transactions.[8]: ch. 5 

Addresses and transactions

Simplified chain of ownership. In practice, a transaction can have more than one input and more than one output.[65]

In the blockchain, bitcoins are linked to specific addresses that are hashes of a public key. Creating an address involves generating a random private key and then computing the corresponding address. This process is almost instant, but the reverse (finding the private key for a given address) is nearly impossible.[8]: ch. 4  Publishing a bitcoin address does not risk its private key, and it is extremely unlikely to accidentally generate a used key with funds. To use bitcoins, owners need their private key to digitally sign transactions, which are verified by the network using the public key, keeping the private key secret.[8]: ch. 5 

Bitcoin transactions use a Forth-like scripting language,[8]: ch. 5  involving one or more inputs and outputs. When sending bitcoins, a user specifies the recipients' addresses and the amount for each output. This allows sending bitcoins to several recipients in a single transaction. To prevent double-spending, each input must refer to a previous unspent output in the blockchain.[65] Using multiple inputs is similar to using multiple coins in a cash transaction. As in a cash transaction, the sum of inputs can exceed the intended sum of payments. In such a case, an additional output can return the change back to the payer.[65] Unallocated input satoshis in the transaction become the transaction fee.[65]

Losing a private key means losing access to the bitcoins, with no other proof of ownership accepted by the protocol.[24] For instance, in 2013, a user lost ₿7,500, valued at US$7.5 million, by accidentally discarding a hard drive with the private key.[66] It is estimated that around 20% of all bitcoins are lost.[67] The private key must also be kept secret as its exposure, such as through a data breach, can lead to theft of the associated bitcoins.[8]: ch. 10 [68] As of December 2017, approximately ₿980,000 had been stolen from cryptocurrency exchanges.[69]

Mining

Bitcoin mining facility with large amounts of mining hardware

The mining process in Bitcoin involves maintaining the blockchain through computer processing power. Miners group and broadcast new transactions into blocks, which are then verified by the network.[62] Each block must contain a proof of work (PoW) to be accepted,[62] involving finding a nonce number that, combined with the block content, produces a hash numerically smaller than the network's difficulty target.[8]: ch. 8  This PoW is simple to verify but hard to generate, requiring many attempts.[8]: ch. 8  PoW forms the basis of Bitcoin's consensus mechanism.[70]

The difficulty of generating a block is deterministically adjusted based on the mining power on the network by changing the difficulty target, which is recalibrated every 2,016 blocks (approximately two weeks) to maintain an average time of ten minutes between new blocks. The process requires significant computational power and specialized hardware.[8]: ch. 8 [71]

Miners who successfully find a new block can collect transaction fees from the included transactions and a set reward in bitcoins.[72] To claim this reward, a special transaction called a coinbase is included in the block, with the miner as the payee. All bitcoins in existence have been created through this type of transaction.[8]: ch. 8  This reward is halved every 210,000 blocks until ₿21 million,[b] with new bitcoin issuance slated to end around 2140. Afterward, miners will only earn from transaction fees. These fees are determined by the transaction's size and the amount of data stored, measured in satoshis per byte.[73][65][8]: ch. 8 

The proof of work system and the chaining of blocks make blockchain modifications very difficult, as altering one block requires changing all subsequent blocks. As more blocks are added, modifying older blocks becomes increasingly challenging.[74][62] In case of disagreement, nodes trust the longest chain, which required the greatest amount of effort to produce.[70] To tamper or censor the ledger, one needs to control the majority of the global hashrate.[70] The high cost required to reach this level of computational power guarantees the security of the bitcoin blockchain.[70]

Bitcoin mining's environmental impact is controversial and has attracted the attention of regulators, leading to restrictions or incentives in various jurisdictions.[75] As of 2022, a non-peer-reviewed study by the Cambridge Centre for Alternative Finance (CCAF) estimated that bitcoin mining represented 0.4% of global electricity consumption.[76] Another 2022 non-peer-reviewed commentary published in Joule estimated that bitcoin mining was responsible for 0.2% of world greenhouse gas emissions.[77] About half of the electricity used is generated through fossil fuels.[78] Moreover, mining hardware's short lifespan results in electronic waste.[79] The amount of electrical energy consumed, and the e-waste generated, is comparable to that of Greece and the Netherlands, respectively.[79][77]

Privacy and fungibility

Bitcoin is pseudonymous, with funds linked to addresses, not real-world identities. While the owners of these addresses are not directly identified, all transactions are public on the blockchain. Patterns of use, like spending coins from multiple inputs, can hint at a common owner. Public data can sometimes be matched with known address owners.[80] Bitcoin exchanges might also need to collect personal data as per legal requirements.[81] For enhanced privacy, users can generate a new address for each transaction.[82]

In the Bitcoin network, each bitcoin is treated equally, ensuring basic fungibility. However, users and applications can choose to differentiate between bitcoins. While wallets and software treat all bitcoins the same, each bitcoin's transaction history is recorded on the blockchain. This public record allows for chain analysis, where users can identify and potentially reject bitcoins from controversial sources.[83] For example, in 2012, Mt. Gox froze accounts containing bitcoins identified as stolen.[84]

Wallets

Screenshot of Bitcoin Core
A paper wallet with the address as a QR code while the private key is hidden
A hardware wallet which processes bitcoin transactions without exposing private keys

Bitcoin wallets were the first cryptocurrency wallets, enabling users to store the information necessary to transact bitcoins.[85][8]: ch. 1, glossary  The first wallet program, simply named Bitcoin, and sometimes referred to as the Satoshi client, was released in 2009 by Nakamoto as open-source software.[7] Bitcoin Core is among the best known clients. Forks of Bitcoin Core exist such as Bitcoin Unlimited.[86] Wallets can be full clients, with a full copy of the blockchain to check the validity of mined blocks,[8]: ch. 1  or lightweight clients, just to send and receive transactions without a local copy of the entire blockchain.[87] Third-party internet services called online wallets store users' credentials on their servers, making them susceptible of hacks.[88] Cold storage protects bitcoins from such hacks by keeping private keys offline, either through specialized hardware wallets or paper printouts.[89][8]: ch. 4 

Scalability and decentralization challenges

Nakamoto limited the block size to one megabyte.[90] The limited block size and frequency can lead to delayed processing of transactions, increased fees and a Bitcoin scalability problem.[91] The Lightning Network, second-layer routing network, is a potential scaling solution.[8]: ch. 8 

Research shows a trend towards centralization in bitcoin as miners join pools for stable income.[24]: 215, 219–222 [92]: 3  If a single miner or pool controls more than 50% of the hashing power, it would allow them to censor transactions and double-spend coins.[61] In 2014, mining pool Ghash.io reached 51% mining power, causing safety concerns, but later voluntarily capped its power at 39.99% for the benefit of the whole network.[93] A few entities also dominate other parts of the ecosystem such as the client software, online wallets, and simplified payment verification (SPV) clients.[61]

Economics and usage

Bitcoin's theoretical roots and ideology

External videos
video icon The Declaration Of Bitcoin's Independence, BraveTheWorld, 4:38

According to the European Central Bank, the decentralization of money offered by bitcoin has its theoretical roots in the Austrian school of economics, especially with Friedrich von Hayek's book The Denationalization of Money, in which he advocates a complete free market in the production, distribution and management of money to end the monopoly of central banks.[94]: 22  Sociologist Nigel Dodd, citing the crypto-anarchist Declaration of Bitcoin's Independence, argues that the essence of the bitcoin ideology is to remove money from social, as well as governmental, control.[95] The Economist describes bitcoin as "a techno-anarchist project to create an online version of cash, a way for people to transact without the possibility of interference from malicious governments or banks".[96] These philosophical ideas initially attracted libertarians and anarchists.[97] Economist Paul Krugman argues that cryptocurrencies like bitcoin are only used by bank skeptics and criminals.[98]

Recognition as a currency and legal status

Legal status of bitcoin
  Legal tender (bitcoin is officially recognized as a medium of exchange)
  Permissive (legal to use bitcoin, with minimal or no restrictions)
  Restricted (some legal restrictions on the usage of bitcoin)
  Contentious (interpretation of old laws, but bitcoin is not directly prohibited)
  Prohibited (full or partial prohibition on the use of bitcoin)
  No data (no information available)

Money serves three purposes: a store of value, a medium of exchange, and a unit of account.[99] According to The Economist in 2014, bitcoin functions best as a medium of exchange.[99] In 2015, The Economist noted that bitcoins had three qualities useful in a currency: they are "hard to earn, limited in supply and easy to verify".[100] However, a 2018 assessment by The Economist stated that cryptocurrencies met none of these three criteria.[96] Per some researchers, as of 2015, bitcoin functions more as a payment system than as a currency.[24] In 2014, economist Robert J. Shiller wrote that bitcoin has potential as a unit of account for measuring the relative value of goods, as with Chile's Unidad de Fomento, but that "Bitcoin in its present form ... doesn't really solve any sensible economic problem".[101] François R. Velde, Senior Economist at the Chicago Fed, described bitcoin as "an elegant solution to the problem of creating a digital currency".[102] David Andolfatto, Vice President at the Federal Reserve Bank of St. Louis, stated that bitcoin is a threat to the establishment, which he argues is a good thing for the Federal Reserve System and other central banks, because it prompts these institutions to operate sound policies.[103]

The legal status of bitcoin varies substantially from one jurisdiction to another. Because of its decentralized nature and its global presence, regulating bitcoin is difficult. However, the use of bitcoin can be criminalized, and shutting down exchanges and the peer-to-peer economy in a given country would constitute a de facto ban.[104] The use of bitcoin by criminals has attracted the attention of financial regulators, legislative bodies, and law enforcement.[105] Nobel-prize winning economist Joseph Stiglitz says that bitcoin's anonymity encourages money laundering and other crimes.[106] This is the main justification behind bitcoin bans.[10] As of November 2021, nine countries applied an absolute ban (Algeria, Bangladesh, China, Egypt, Iraq, Morocco, Nepal, Qatar, and Tunisia) while another 42 countries had an implicit ban.[107][needs update] Bitcoin is only legal tender in El Salvador.[4]

Use for payments

Café in Delft accepting Bitcoin

As of 2018, Bitcoin is rarely used in transactions with merchants,[108] but it is popular to purchase illegal goods online.[109][110] Prices are not usually quoted in bitcoin and trades involve conversions into fiat currencies.[24] Commonly cited reasons for not using Bitcoin include high costs, the inability to process chargebacks, high price volatility, long transaction times, and transaction fees (especially for small purchases).[108][111] Bloomberg reported that bitcoin was being used for large-item purchases on the site Overstock.com and for cross-border payments to freelancers.[112] As of 2015, there was little sign of bitcoin use in international remittances despite high fees charged by banks and Western Union who compete in this market.[24][113]

In September 2021, the Bitcoin Law made bitcoin legal tender in El Salvador, alongside the US dollar.[4] The adoption has been criticized both internationally and within El Salvador.[4][114] In particular, in 2022, the International Monetary Fund (IMF) urged El Salvador to reverse its decision.[115] As of 2022, the use of Bitcoin in El Salvador remains low: 80% of businesses refused to accept it despite being legally required to.[116] In April 2022, the Central African Republic (CAR) adopted Bitcoin as legal tender alongside the CFA franc,[117] but repealed the reform one year later.[118]

Bitcoin is also used by some governments. For instance, the Iranian government initially opposed cryptocurrencies, but later saw them as an opportunity to circumvent sanctions.[119] Since 2020, Iran has required local bitcoin miners to sell bitcoin to the Central Bank of Iran, allowing the central bank to use it for imports.[120] Some constituent states also accept tax payments in bitcoin, including Colorado (US)[121] and Zug (Switzerland).[122] As of 2023, the US government owned more than $5 billion worth of seized bitcoin.[123][124]

Use for investment and status as an economic bubble

Government website with El Salvador reserves in May 2024

As of 2018, the overwhelming majority of bitcoin transactions took place on cryptocurrency exchanges.[108] Since 2014, regulated bitcoin funds also allow exposure to the asset or to futures as an investment.[125][126] Individuals and companies such as the Winklevoss twins[127] and Elon Musk's companies SpaceX and Tesla have massively invested in Bitcoin.[128][129] Bitcoin wealth is highly concentrated, with 0.01% holding 27% of in-circulation currency, as of 2021.[130] As of September 2023, El Salvador had $76.5 million worth of bitcoin in its international reserves.[131]

In 2018, research published in the Journal of Monetary Economics concluded that price manipulation occurred during the Mt. Gox bitcoin theft and that the market remained vulnerable to manipulation.[132] Research published in The Journal of Finance also suggested that trading associated with increases in the amount of the Tether cryptocurrency and associated trading at the Bitfinex exchange accounted for about half of the price increase in bitcoin in late 2017.[133][134]

Bitcoin, along with other cryptocurrencies, has been described as an economic bubble by several economists, including Nobel Prize in Economics laureates, such as Joseph Stiglitz,[135] James Heckman,[9] and Paul Krugman.[98] Another recipient of the prize, Robert Shiller, argues that bitcoin is rather a fad that may become an asset class. He describes its price growth as an "epidemic", driven by contagious narratives.[136]

According to research published in the International Review of Financial Analysis in 2018, Bitcoin as an asset is highly volatile and does not behave like any other conventional asset.[137] According to one 2022 analysis published in The Journal of Alternative Investments, bitcoin was less volatile than oil, silver, US Treasuries, and 190 stocks in the S&P 500 during and after the 2020 stock market crash.[138] The term hodl was created in December 2013 for holding Bitcoin rather than selling it during periods of volatility.[139][140]

Economists, investors, and the central bank of Estonia have described bitcoin as a potential Ponzi scheme.[141][142][143] Legal scholar Eric Posner disagrees, however, as "a real Ponzi scheme takes fraud; bitcoin, by contrast, seems more like a collective delusion".[144] A 2014 World Bank report also concluded that bitcoin was not a deliberate Ponzi scheme.[145]

See also

Notes

  1. ^ a b Named after Satoshi Nakamoto.
  2. ^ a b The exact number is ₿20,999,999.9769.[8]: ch. 8 

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