The comment is a developer guideline.
It is not visible to the web page. Its purpose is only to know in the future what you did, or guideline for future modification.
It is recommended to add comment in the complex code to improve code readability.
The written comments are not executed and ignored by the web browser.
HTML comment is written in between <!-- --> tags. This pair of tags used in both single line and multi line comments.
Single Line Comment
<!-- This is Single Line Comment. -->
Multi Lines Comment
<!-- This is multi line comment supported in HTML. -->
<html> <!-- Start Header tag --> <head> <!-- Title of the Document is written here--> <title>Welcome to eTutorialspoint.</title> </head> <body> <!-- Content within the body tag displays on the webpage. --> <p>Paragraph contents..........</p> </body> </html>