When note text is very long, endnotes might be best.
Because footnotes appear at the bottom of the page, readers can see them in context, when the source material or an additional explanation might be most useful. On the other hand, if sources or supplementary information can be looked at afterward, endnotes might be best.
Then again, there's less space to enter note text at the bottom of the page in a footnote. If a footnote is very long, it will continue on to the bottom of the next page. In that case, you might want to use an endnote instead. There's advice about adjusting footnote length in the Quick Reference Card at the end of the course.
Whether to use footnotes or endnotes may be determined by your preference, by your publisher, or by the style guidelines of your workplace. Both footnotes and endnotes can be used in the same document.