Answer

HTML Comments are not displayed on a web page and are useful in documenting source code.

A comment starts with <!-- and ends with --> as shown below.

List Type Description
Single line comment A comment that starts and ends on the same line.
Multiple line comment A comment that can extend to multiple lines.
Inline comment A comment that exists within the content of an element.

Example

<!DOCTYPE html>
<html>
<head>
</head>
<body>
    <h1>HTML Comments</h1>
    <!-- Single line comment -->
    <!-- 
        Multiple line comment
        that extend to multiple lines
    -->
    <p>This paragraph contains <!-- inline comment goes here --> an inline comment.</p>
</body>
</html>

In the below example, we have used all the different types of comments.