Endnotes
Endnotes is a simple solution for adding footnotes to your WordPress posts or pages. The plugin originated as a fork of John Watson’s FD Footnotes but has been updated to use the WordPress Settings API. The original plugin’s usage and functionality has been retained.
How to Use
You can add footnotes to your posts or pages by adding numbered inline content within square brackets. Place the inline content where you would like the superscript numeral to appear.
I am Jack's happy sentence that will contain a footnote[1. I am Jack's happy footnote] for calling out a reference.
Each footnote must have a number, followed by a period and a space, and then the actual footnote. They don’t have to be unique but it is recommended. It doesn’t matter what the numbers are since the footnotes will be automatically renumbered when the post is displayed.
Footnotes can contain anything you’d like including links, images, etc. Footnotes are automatically linked back to the spot in the text where the note was made.
Square Bracket Usage
Do not include square brackets inside the footnotes themselves.
Unique Footnote Numbers
Footnote numbers don’t need to be unique but it is highly recommended, especially if the text is identical for multiple footnotes. If you have multiple footnotes with the exact same text and number, you may get undesirable results.