Using footnotes helps keep your main content clean and focused. A footnote can provide additional context without interrupting the reading flow for your audience and is excellent for properly citing sources, references, or side notes.
You can use inline footnotes by writing your text subject followed by a marker like some-text[^1] (where 1 is an arbitrary value). Then, you can reference the footnote at the bottom of your content with [^1]: This is a footnote..
The example in the screenshot below shows a simple implementation of footnotes on this blog:
Notice the return symbol (↩︎), which allows a reader to jump back to the reference point in your post.
Footnotes are common in academic writing and on many blogs where additional content enhances credibility. I have personally not used them on this blog, but I think I have a use case in mind.