What purpose we use <!--This a comment-->

Answer 1

You're right. To comment it.

Answer 2

It is an explanatory way to make the code user-friendly​

Answer 3

https://code.sololearn.com/W7X805sc4DPC/?ref=app

Answer 4

With a comment you can also define specific sections like after the main section in your html you can write <! - - End main section - - > so it's not only user friendly, also other developers can read the code better. And if you want to test some lines of code and are not sure if you need/want that you can put that code into a <! - - "lines of code" - - >