What are the uses of comments?

Answer 1

<!--
Just to know why you wrote the line of code below or above the comment
-->
It cannot be executed but helps to programmer to know why he inserted a particular line of code in the programmer

Answer 2

comments are helpful for better understanding of code like where u used which functions and for what purposes this makes u easily remember the code...

Answer 3

In html (you used the "html" tag), strongly nested <div> blocks with lots of text in between can be difficult to follow. Remember that the closing tag does not come with the same information as a leading <div id="stuff" class="otherstuff">. It is just </div>.

I always found comments very helpful to maintain some overview:

<div class"="this">
...
<div class"="that">
...
<div class"="something">
...
</div> <!-- end of something -->
</div> <!-- end of that -->
</div> <!-- end of this -->