A footnote is a note placed at the bottom of an article that expands on a section of the text. The connection between a portion of text and its footnote is indicated by a number or symbol that appears after the text.

Footnotes are useful for material that would be distracting if included in the main text, yet is helpful in explaining a point in greater detail. They are also used to cite sources. Wikipedia:Verifiability, a key content policy, says that any material that is challenged or likely to be challenged, including any contentious material about living persons, and all quotations, must have a source. Unsourced material may be removed from any article - and if it is, the burden of proof is on the editor who wishes to restore it.

Footnotes are one way to cite sources. Alternative methods are embedded links and Harvard referencing (also known as author-date or parenthetical referencing). For more information, see Wikipedia:Citing sources, the main style guide on citations.

You can add a footnote to an article by writing your note within <ref> ... </ref> tags, as explained below.

A very simplified explanation is given at Help:Footnotes

1. Place a <ref> ... </ref> where you want a footnote reference number to appear in an article—type the text of the note between the ref tags.
2. Place the {{reflist}} tag in a "Notes" or "References" section near the end of the article—the list of notes will be generated here.

This page itself uses footnotes, such as the one at the end of this sentence.^[1] If you view the Wikicode of this page by clicking "Edit this page," you can see a working example of footnotes. For the purpose of adding references, the more recent cannot be mixed on a page with the old Footnotes3 format—you must pick one or the other. It is possible, however, to use the template system to e.g. separate content notes and references when that is deemed a good idea (this is often the case when content notes must be themselves cited, see, for example, Alcibiades). However, as with all citation styles, consensus should be achieved on the talk page before implementing such a change.

Where to place reference tags

Wikipedia's house style is that ref tags are placed at the end of the term, phrase, sentence, or paragraph to which the footnote refers.^[2] This is the format recommended by the Chicago Manual of Style.

When placed at the end of a clause or sentence the ref tag should be directly after the punctuation mark without an intervening space, in order to prevent the reference number wrapping to the next line. The same is true for successive ref tags.^[1] The exception is a dash — which should follow the ref tag, as recommended by the Chicago Manual of Style.^[3]

Example:

According to scientists, the Sun is pretty big;<ref>Miller, E: "The Sun.", page 23. Academic Press, 2005.</ref>
however, the moon is not so big.<ref>Smith, R: "Size of the Moon", ''Scientific American'', 46(78):46.</ref>

== Notes ==
<references />

Citing a footnote more than once

To give a footnote a unique identifier, use <ref name="name"> ... </ref>. You can then refer to the same footnote again by using a ref tag with the same name. The name cannot be a number, or the extension will return an error. The ref name need not be placed within quotes unless it consists of more than one word (the wiki parser converts single word quoteless attribute values into validly quoted XHTML).

Though some printed texts use ibid, ditto, or similar shorthand for multiple references, Wiki is not paper. Please do not use "ibid" or other footnote shorthands. The available tools for multiple references are more powerful.

Only the first occurrence of text in a named ref will be used, although that occurrence may be located anywhere in the article. You can either copy the whole footnote, or you can use a terminated empty ref tag that looks like this: <ref name="name"/>. Such forward-slash-terminated named tags may precede the definition of the named reference.^[4]

In the following example, the same source is cited three times.

This is an example of multiple references to the same footnote.<ref name="multiple"/>

Such references are particularly useful when citing sources, if different statements come from the same source.<ref name="multiple">Remember that when you refer to the same footnote multiple times, the text from the first reference is used.</ref>

A concise way to make multiple references is to use empty ref tags, which have a slash at the end.<ref name="multiple">This text is superfluous, and won't show up anywhere. We may as well just use an empty tag.</ref>

== Notes ==
<references />

The text above gives the following result in the article (see also Notes section below):

This is an example of multiple references to the same footnote.^[5]

Such references are particularly useful when citing sources, when different statements come from the same source.^[5]

A concise way to make multiple references is to use empty ref tags, which have a slash at the end.^[5]

One should be particularly careful when deleting one of multiple named references, because the footnote text will be deleted unless it is copied to another ref tag with the same name.

Citation templates

Text placed between <ref> and </ref> may be short notes or full bibliographic references, and may be formatted either by hand or with the assistance of templates. Instructions on available templates to help format bibliographic references may be found at Wikipedia:Citation templates. Use of such templates is not required; see WP:CITE.

• Avoid using Ibid or similar abbreviations in footnotes. Other editors who add new references to the article may not take the time to correct Ibid references broken by their addition. Furthermore, not all readers are familiar with the meaning of the term. If a reference is reused in more than one footnote, it is preferable to use the format "Smith, Short Title, 182" rather than "Ibid, 182", so as to avoid these problems, or use named references if appropriate.
• Consider maintaining a separate bibliography/references section that gives full publication details for frequently cited sources, then you only need to cite the author, short title, and page number in specific notes, following Wikipedia:Citing sources. For example see Johannes Kepler and Rabindranath Tagore.
• Internal links and wiki formatting work as normal within the text of the citation, like this: <ref>''[[Wikipedia]]'', [[18 March]], [[2007]].</ref> However, you cannot rely on the "pipe trick" to expand a link for you in ref text; you must type out [[George Clark (historian)|George Clark]], instead of just typing [[George Clark (historian)|]] and letting the software fill in the text after the pipe. See Help:Pipe_trick#Cite.php_footnotes_and_the_pipe_trick.
• Do not use <ref> tags within templates. They are not numbered correctly. See m:Cite.php#Current_problems, and User:Pengo/pageusingref for an illustration of the issue. Ref tags may also not handle template parameters correctly.
• References cannot be nested: <ref name="Ran1912">J. Random, 1912. Cited in <ref name="Foo2005"/></ref> does not render correctly.

Some editors make the references smaller. Although smaller text has several disadvantages, it is common with very long lists of references to substitute the basic <references /> tag with {{Reflist}}, which reduces the text size to 90%. {{Reflist}} should not be used with a "subst:". The underlying CSS class is "references-small", which may be used directly as <div class="references-small"><references /></div>. If this class is used to make other sections small for consistency (e.g. notes, references, see also, external links sections), the div tags must be opened and closed within each section.

A similar CSS class exists to create small footnotes in two (or optionally, three) columns, but this displays as a single column in some common browsers. If desired, use {{Reflist|2}} or the CSS class directly with <div class="references-2column"><references /></div>

As of late December 2005, the Cite.php extension to MediaWiki has been installed on all Wikimedia wikis. Other wikis that use the MediaWiki software may not have this extension installed, and therefore may be unable to display Cite.php footnotes. The Special:Version page on a MediaWiki wiki shows the installed extensions.

See Meta:Cite/Cite.php for a technical explanation of the Cite.php extension on Meta-Wiki.

An older system using {{ref}} and {{note}} templates is still common. Converting this older system^[6] to the new <ref>...</ref> system can make the references in an article easier to maintain.

Converting citation styles should not be done without first gaining consensus for the change on the article's talk page.

A December 2005 ArbCom case ruled that the following scripts could no longer be used by a certain Wikipedian:

• Wikipedia:Footnote3/numlink2note.pl, explained at Wikipedia talk:Footnote3/numlink2note.pl
• Wikipedia:Footnote3/order-footnote.pl, explained at Wikipedia talk:Footnote3/order-footnote.pl

Similarly, individual users may be forbidden to "manually convert citation styles on any articles."

So, tread lightly, and seek consensus first, before converting citation styles. For example, when using (semi-)bot tools as listed below:

• User:Cyde/Ref converter converts articles that use the {{ref}} and {{note}} system into the more recent m:Cite.php system;
• Citation Tool diagnoses and fixes sequencing and duplication errors in m:Cite.php references. In the future, Citation Tool may (optionally) enable user-guided conversion of some or all of the <ref> numbered citations to named notes using the footnote3 template technology (which includes Harvard references).

CAUTION: do not edit-war with automated tools that convert in opposing directions.

• Wikipedia:Verifiability, the relevant policy regarding what material should be cited
• Wikipedia:Citing sources, the relevant style guide.
• Wikipedia:Citing sources/example style, listing also several examples of non-numbered APA style and Harvard referencing techniques
• Wikipedia:Template messages/Sources of articles for complete list of templates that are available for citations; note that several of these templates can easily be combined with "footnote3" footnotes, see Gymnopédie#Notes and references for an example.
• Wikipedia:WikiProject Wikicite: Proposal for use of database of citations.
• Wikipedia:WikiProject Fact and Reference Check
• Other types of numbered footnotes:
  • Wikipedia:Footnote1, a very old, manually-numbered footnote system that should not be used.
  • Wikipedia:Footnote2, another obsolete system that should not be used.
  • Wikipedia:Footnote3, an automatically-numbered footnote system using templates, which is widely used but has been replaced by MediaWiki footnotes.
• Help:Footnotes
• meta:Cite.php - description of the <ref>...</ref>/<references/> system at metawiki
• meta:Biblio - Biblio.php, an extension of Mediawiki which provides a citation manager. (beta maturity)
• Wikipedia:Ref reform
• Bug 2745: Have References text edit window on Edit pages.
• Template:Rp - adds ability to handle Harvard-style page number citations to Cite.php inline references (intended for use when one source is cited a large number of times, and would produce either too many individual entries under <references /> for the same source, or one exceedingly long entry that cited too many pages to possibly be useful to readers).

1. Additional references that are not created with <ref> ... </ref> (as per WP:CITE, section 3.5.2) do not continue the numbering.