HTML Comment Tags
You can add comments to your HTML source by using the following syntax:<!-- Write your comments here -->
Comments are not displayed by the browser, but they can help document your HTML.
With comments you can place notifications and reminders in your HTML:
Example
<!-- This is a comment -->
<p>This is a paragraph.</p>
<!-- Remember to add more information here -->
Comments are also great for debugging HTML, because you can comment out HTML lines of code, one at a time, to search for errors:
Example
<!-- Do not display this at the moment
<img border="0" src="pic_mountain.jpg" alt="Mountain">
-->
Conditional Comments
You might stumble upon conditional comments in HTML:
<!--[if IE 8]>
.... some HTML here ....
<![endif]-->
Conditional comments defines HTML tags to be executed by Internet Explorer only.
Software Program Tags
HTML comments tags can also be generated by various HTML software programs.For example <!--webbot bot--> tags wrapped inside HTML comments by FrontPage and Expression Web.
As a rule, let these tags stay, to help support the software that created them.