Specific CSS?

Hello,
I recently came across a stylesheet with the following line:

ul#nav > li > a:hover

This got me wondering - what is the difference between that and this?

ul#nav li a:hover

Any ideas?
Thanks

The second rule will select anchors in list items on any level while the first selects only direct children.


<ul id="nav">
<li>
<a>link selected with rule 1 & 2</a>
<ul>
<li><a>link selected with rule 2 only, ignored by rule 1</a></li>
</ul>
<li>
</ul>

Got it - awesome! Thank you.