Footnote

A footnote is a numbered note attached to a specific point in a text and printed at the bottom of the same page. It has two traditional jobs: to give the source for a quotation or claim, and to hold material — a qualification, a counter-example, a bibliographic detour — that would break the rhythm of the main argument if it were left in the body.

The device became standard in European scholarship in the seventeenth century, as historians and biblical scholars needed a way to show their working without cluttering their prose. It matured in the nineteenth century into the elaborate apparatus of German Wissenschaft, where a single page could carry more footnote than text. The historian Anthony Grafton's book 'The Footnote: A Curious History' remains the standard account.

Footnotes differ from endnotes chiefly in convenience. A footnote sits under the reader's eye; an endnote requires a trip to the back of the book. Serious readers prefer footnotes for exactly this reason, and serious publishers of academic work still set them at the foot of the page. Trade publishers often prefer endnotes because they leave the page clean.

Common mistakes: using footnotes to hide claims that belong in the main text; using them as a place to argue with critics; letting them balloon until they compete with the argument they support. The rule of thumb: a footnote should either give a source, add a genuine qualification, or be cut.