Hidden comments are often ignored by most website designers, however they can be very helpful. For example lets say you are designing a website with a friend, you finish designing the index page and upload it online. Your friend can then simply download that page and view its code and use the hidden comments you inserted to quickly be able to see which section is designated for what. As an example take a look at the bit of code below and see how we have used hidden comments:
<!-- Title Line and Table-->
<tr>
<td>
<table border="0" cellpadding="3"
cellspacing="0" width="100%">
<tr>
<td align=center class=row1 width=25%>
<!-- Topic Link and Image--><br><!--
Topic Link and Name--></td><td width=75% class=infort
valign=top align=left><br><br><!-- Main Story -->
<br><br><br> <!-- Date Posted--><br>(<!--
Comments Number and Link to Comments--> | <!-- Category
Link and Name--> | <!-- Story Score-->)
</td>
</tr>
</table>
</td>
</tr>
<!-- Story Footer Table-->
Hidden comments are never interpreted by the browser, anything between <!-- and --> is always ignored, even if you insert code into it. I hope that this tutorial has cleared up a thing or two about hidden comments that I have recieved some emails about.