Markdown's best feature^[1], in my humble opinion, is how easily you can insert footnotes. They can be links like this^[2], or commentary^[3]. When you add a footnote, you insert [^this] into your text, and elsewhere in the document (even before your anchor!) you add [^this]:https://your-link. You can put them in any order, or use any word or number for the anchor, and the rendered document will have them numbered in the correct order.

Technically, this is the "extended syntax" because it's not part of what John Gruber originally proposed for Markdown^[4]. Of course, Markdown has taken on a life of its own since then, and the extended syntax has given us so much.

Here's the raw Markdown text of this blog post as an example of how wild you can get with setting up your footnotes:

Markdown's best feature[^documentation], in my humble opinion, is how easily you can insert footnotes. They can be links like this[^link], or commentary[^comment]. When you add a footnote, you insert `[^this]` into your text, and elsewhere in the document (even before your anchor!) you add `[^this]:https://your-link`. You can put them in any order, or use any word or number for the anchor, and the rendered document will have them numbered in the correct order.

[^origin]:https://daringfireball.net/projects/markdown/


Technically, this is the "extended syntax" because it's not part of what John Gruber originally proposed for Markdown[^origin]. Of course, Markdown has taken on a life of its own since then, and the extended syntax has given us so much.

[^documentation]:https://www.markdownguide.org/extended-syntax/#footnotes
[^link]:https://www.reddit.com/r/discworld/comments/8nzsf8/what_is_everyones_favourite_footnote/
[^comment]:Like this!