Just like Microsoft Word has the ability to create subscript and superscript text, the same can be achieved in HTML. The <sub> and <sup> tags are a simple addition to your list of tags — they are not included in the CAT curriculum.

I always suggest that learners create a footer with a copyright symbol and their name on all their HTML pages:

<footer>
    <p><sup>&copy;</sup>Initial Surname</p>
</footer>

Read the post HTML entities for information on the copyright symbol and more.

Read the post Creating a fixed footer with CSS for more information about creating a footer section for your web pages.