The text can be defined as subscript using <sub> and superscript using <sup> tags. These tags are much useful in chemical formula and some mathematical equations. Superscript [1] also used on a text line to have a footnote and the Subscript [2] is for scientific formulae.
Example Code:
This is a <sub>subscript</sub> example
This is a <sup>superscript</sup> example
Result:
This is a subscript example
This is a superscript example
The <sub>,<sup> can also be used along with the CSS.