A footnote is a notation at the bottom of the page in a printed document. Footnotes are usually presented in smaller print than the dominant text, and they are used for a variety of purposes. The “foot” in “footnote” refers to the fact that the notation is located in the “footer” or “bottom” of the document. A similar concept is the endnote, a note which is provided at the end of a document, rather than at the bottom of a specific page.

When a text has footnotes, they are indicated with various symbols or superscript numbers. The asterisk symbol, *, is a common symbol for footnotes, but a variety of symbols including daggers, †, may be used. In a text with a lot of footnotes, numbers are usually used to indicate footnotes, so that the reader can keep track of what is going on. Endnotes are typically indicated with numbers, to make it easier for people to look them up.

Different style manuals have different rules about using footnotes, and it is important to follow style guidelines when submitting material for publication. Because footnoting can get very complicated, most style guidelines devote at least a few pages to the footnote. Some people avoid using footnotes at all, while others relish footnotes, because footnotes provide a great degree of freedom when they are used well.

One common reason for footnoting is to provide citations. Whenever an author quotes someone else or discusses someone else's ideas, he or she is expected to provide a citation, both to provide credit and to allow readers to examine the source for themselves. Some style guidelines like citations inline in the text, as in “(Myers, 2006)”, while others prefer to see citations footnoted. Footnoting citations allows readers to focus on the text, consulting the citation whenever they feel like it, rather than being forced to read it.

Footnotes really flourish in the sense of additional commentary. Authors may use a footnote to provide comments or extra information, especially if that information digresses. Academics in particular cannot resist sharing interesting tidbits with their readers, but these tidbits may not be strictly relevant to the text at hand. Using a footnote allows authors to talk about matters which may be of interest without detracting from the primary focus of the text. Sometimes, the footnotes take up more room on the page than the actual text.

It is not uncommon to see footnotes used to make humorous asides. For people who enjoy academic jokes, footnotes are often a great source for amusing comments and side notes which would not be appropriate in the central text. Footnotes may also be used to recount anecdotes or to provide a subtle commentary on the source or topic being discussed.