Conditional Comments are basically a new set of comment-like tags that IE 5+ supports. These tags look very much like the good old comment tag and in fact are treated as such by all browsers except IE, in which they operate a little more intelligently. Using Conditional Comments, you can selectively “comment out” any portion of your page in a way that only IE interprets the containing content, or the other way around.

This is a good and valid alternative to invalid browser specific CSS hacks we used ealier.

<!--[if IE]>
You are using Internet Explorer.
<![endif]-->

<!--[if IE 5]>
You are using Internet Explorer 5.
<![endif]-->

<!--[if IE 5.0]>
You are using Internet Explorer 5.0.
<![endif]-->

<!--[if IE 5.5]>
You are using Internet Explorer 5.5.
<![endif]-->

<!--[if IE 6]>
You are using Internet Explorer 6.
<![endif]-->

<!--[if IE 7]>
You are using Internet Explorer 7.
<![endif]-->

<!--[if gte IE 5]>
You are using Internet Explorer 5 and up.
<![endif]-->

<!--[if lt IE 6]>
You are using Internet Explorer lower than 6.
<![endif]-->

<!--[if lte IE 5.5]>
You are using Internet Explorer lower or equal to 5.5.
<![endif]-->

<!--[if gt IE 6]>
You are using Internet Explorer greater than 6.
<![endif]-->

<!--[if !IE]>
You are NOT using IE.
<![endif]-->