If you want to use certain text in subscript or Superscript on your HTML webpages, then you can do that by using the HTML tags.

For Subscript, the HTML tag is <sub>. By using the subscript tag, the text within the tag is rendered slightly below the normal text, in a small font-size.

For Superscript, the HTML tag is <sup>. By using the superscript tag, the text within the tag is rendered slightly above the normal text, in a small font-size. It is widely used for typing mathematical equations, chemistry equations, etc.