HTML <sup> Tag
E = mc<sup>2</sup>
The above example demonstrates usage of the
<sup> element represents superscript. In some languages, superscripts are part of the typographical conventions for some abbreviations. A superscript is also often used in mathematical expressions.
The HTML5 specification states that
<sup> element must only be used only to mark up typographical conventions with specific meanings, not for typographical presentation for presentation's sake.
Also see the <sub> element for marking up subscripts.