How do <sub> and <super> operate exactly?

Question

I mean I know, they're styling for font, but like how does the machine know which letter or number to subscript or superscript? Like in H2O.. I've also tried on Decoder(android) the text stayed the same? Nothing went up or down, am I doing anything wrong or.. just curious I think it's important to understand everything even little lol..

Answer 1

It's for subscript and superscript you can try writing H₂O

Answer 2

https://www.sololearn.com/Discuss/1935112/what-is-subscript-text-and-superscript-text

Answer 3

https://code.sololearn.com/W5JoY7ZE6ryY/?ref=app

Answer 4

It wasn't written like that in the lesson of html formats, that's why I asked! it seems logical.. why didn't I think of it that way? The something we want to "sub""sup" should be in-between to take effect! Thank you:)