This help page is a how-to guide. It explains concepts or processes used by the Wikipedia community. It is not one of Wikipedia's policies or guidelines and may reflect varying levels of consensus.

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This page explains the use of the reftag element, <ref>...</ref> for defining reference footnotes, as displayed by using a <references /> tag or a {{Reflist}} template to list the footnotes. A reftag can also be defined by using wikitext function {{#tag:ref|...}} to generate the text <ref>...</ref> and allow direct use of subst'ing of templates to embed equivalent markup inside a footnote, or to nest a <ref>...</ref> inside a {{#tag:ref|...}}.

The general format is <ref>text</ref> for a simple reftag footnote. However reftags can have a name="xx" to define a footnote to be reused on a page by named ref, <ref name="xx" />, as when citing the same webpage at several spots in the article text. There can be more than 3,000 reftag footnotes defined on a page, but usually there are less than a hundred.^{[fn 1]}

When citing different pages in a single source, a named ref^[1] can be followed by a {{R}} template. Given a ref like "<ref name="author1990">book</ref>", the ref "author1990" can be reused, now using a different page number, say 53. This subsequent ref {{R|author1990|p=53}} will show the same superscript number, with a suffix of a colon and, in this case 53, the page number.^[1]: 53 This format allows the reader to click to the reference section, and then click on other references from the same source.

Rather than define hundreds of footnotes in a single list, various reftags could split to some named groupings, such as using <ref group="gg">...</ref> to collect those footnotes into group name "gg" as displayed by <references group="gg" />.^{[fn 2]} For example, a common tactic is to define footnote group "fn" which shows each link as "^{[fn 9]}" for the 9th footnote in the group="fn". A group name can be multiple words in straight double quotation marks (group="set xx yy"), but a single-word name with no punctuation or other special characters, just ASCII letters and numerals, can omit the quotation marks (as: group=fn). Hence, many group names are typically one-word labels, to avoid excessive quotation marks.^{[fn 3]}

Rather than using an element <ref>text</ref>, an alternate method is to use the wikitext function tag:ref, as {{#tag:ref|...text...}} to define the contents of a footnote.

Examples:

• Using {{#tag:ref|Example of tag:ref function}} will show a superscript number: ^[2] and list footnote "Example of tag:ref function" under the References.
• Using named {{#tag:ref|Named reftag function xx1|name="xx1"}} will show a superscript number: ^[3] and list footnote "Named reftag function xx1" under the References below. The footnote name "xx1" then can be reused by putting <ref name="xx1" /> at various points in the text.^[3]

• Wikipedia:Advanced footnote formatting – special layouts
• Wikipedia:Citing sources (WP:CITE) – how to format footnotes or bibliography
• Wikipedia:Reliable sources (WP:RS) – about reputable references
• Wikipedia:Find sources – how to hunt for quality source documents
• {{Cite web}} – most common citation template, for sources with a URL
• {{Cite book}} – to cite a book/chapter or volume as a source reference
• {{Cite journal}} – to cite an article in a periodical as a source reference
• mw:Help:Cite – original documentation of the <ref> citation feature provided by MediaWiki