Sometimes, bloggers may wish to add a footnote to the bottom of their text. To link a word, or phrase, to that footnote, a superscripted number, eg:1, is inserted above the text baseline, to indicate the reference in their text. This would, normally, be in a series, depending on the number of references.
It may even be a chemical formula, eg: H20, where part of the formula needs to be subscripted, or below the baseline of text...eg:
The application of superscripted and/or subscripted indicators, or text, is a very simple matter of adding an html tag1 to your posted text, via the html editor screen.
The 'tag' looks like this <sup> text, or number, to be superscripted </sup>, where the indicator is surrounded by the tags - <sup>....</sup> or <sub>....</sub>
This can be very useful for students, or writers, who reference works. You can also make the indicators, themselves, hyperlinks 2, or anchor links, in this case, to the word 'Sometimes' above. You just need to think about it.
1. Example only
2. W3 Schools.com