In HTML with comments are not displayed by the browser,but they can help document your HTML source code.with comments you can place notifications and reminders in your HTML.the following simple syntax of comments in HTML.
<!-- Your Text Here -- >
<html>
<head>
<title>Paragraphs</title>
</head>
<body>
<!-- This is Simple Comment in This Document -->
<p>This is sample paragraph used with <p> tag.</p>
<p>
The Veewom is largest tutorials and educational website on the internet.
</p>
</body>
</html>
<!--[if IE 9]>
.... some HTML here ....
<![endif]-->