How to Use Footnotes. Part of the series: Teaching & Writing. Footnotes can be used for a variety of purposes, but most commonly they are used to credit someone or to site a source of information or to offer more information or a definition without breaking the flow of the writing. Use footnotes to inform the reader with advice from a writing instructor in this free video on education. Read more: http://www.ehow.com/video_4774676_use...