sub
Definition and Usage
The <sub> tag defines subscript text. Subscript text appears half a character below the normal line, and is sometimes rendered in a smaller font. Subscript text can be used for chemical formulas, like H2O. The HTML<sub> element defines a span of text that should be displayed, for typographic reasons, lower, and often smaller, than the main span of text. The <sub> element is used to identify characters that should be rendered in a subscript position. The element should be used mark text according to typographical conventions and not stylistic purposes. Text that is to appear subscript for purely stylistic purposes should be styled with CSS.