And if you don't know what I am talking about, let me show it to you. (Internet Explorer users will not be able to see the mark)

Netscape users will see a small blue mark near the bottom-right corner of the image. Yep?

The blue mark appears because the image tag and its surrounding anchor tags have been placed on separate lines! If you place them on one line, the mark will not be displayed.

Faulty Code
<A HREF="somepage.html">
<IMG SRC="image.gif" ...>
</A>

Corrected Code
<A HREF="somepage.html"><IMG SRC="image.gif" ...></A>