Usage Recommendation
thumbs up Use it.

<SUB> sets the text as subscripts. This puts the characters lower down than regular text. <SUP> sets the text as superscripts, which puts the characters higher up than regular text.

This Code Makes This
When I visited W<SUP>3</SUP>C
I stopped by the 
H<SUB>2</SUB>O fountain.
When I visited W3C I stopped by the H2O fountain.