Comments are useful in HTML for two main reasons:
1. Writing Notes/Reminders to Yourself Inside of HTML Files
2. Temporarily Hiding Elements/Tags
HTML comments will be ignored by the browser, although they can be viewed in the source code.
Each comment begins with <!-- and ends with -->. Complete HTML elements (all except comment tags!) can be contained within these tags -- anything between them will be ignored.
<title>My Very First Webpage</title>
<!-- How do you know when there is an elephant under your bed? -->
<!-- When your nose touches the ceiling! -->
<!-- <p>(This will not show up on your webpage.)</p> -->