Help:Cite

The cite extension allows you to add citation footnotes to articles.

See mw:Extension:Cite/Cite.php for extension info.

Footnotes in action
The introduction line of this article reads:

The cite extension allows you to add citation footnotes to articles.

The section is the  tags creates a footnote.

At the end of the page is a section called references which includes the code. The footnote text is placed here, and the texts are linked.