The <nowiki> tag is used to suppress the interpretation of Wiki markup. This is often useful to demonstrate or explain Wiki markup language to another user.

Wiki markup (and Wiki tags that resemble HTML tags) that are placed between <nowiki> and </nowiki> are not interpreted, and are displayed on the page just the way they are typed. For example, [[this]] would ordinarily form a wikilink, but since it is placed between <nowiki> and </nowiki>, like this: <nowiki>[[this]]</nowiki>, no such link is formed. This is rarely of use in an actual Wikipedia article.

The <nowiki> tag is helpful, for example, when asking questions at the Teahouse and explaining issues at the Village Pump as well as on an article's Talk page. In this case 'the markup code' can be displayed without being actionable.