Conditional comments work in Internet Explorer and on Windows only. For this reason, you can create special instructions to be executed by Internet Explorer only ( on Windows ). Conditional comments are for Internet Explorer 5 and higher.
The basic structure of a conditional comment is the same as an HTML comment (<!-- -->). When another browser sees such comments, they will simply ignore them.
This code snippet will target Internet Explorer 6:
<!--[if IE 6]>
Special instructions for IE 6 here
<![endif]-->
This code snippet will target Internet Explorer:
<!--[if IE 7]>
According to the conditional comment this is Internet Explorer 7<br />
<![endif]-->
This will target the browser: Internet Explorer and all versions above 5:
<!--[if IE]>
According to the conditional comment this is Internet Explorer<br />
<![endif]-->
