Footnote

A footnote is a note referenced from the text and placed at the bottom of a page or, more rarely, beside the referencing text in a book or document.

A footnote usually contain a reference, a citation, or comments that the author decided not to include within the main body of the text. The footnote is usually referenced in the main text by a superscripted letter, symbol or an ordinal number, but other forms and formats are also common. A special type of note are the endnotes which are similar in most respects to footnotes, but are positioned at the end of a chapter or a book.