Quick Overview

If you want to nest lists in HTML, you probably did something like the following (although you may not have done the indenting)

&lt;ul&gt;<br />
&nbsp;&nbsp;&lt;li&gt;List Item 1&lt;/li&gt;<br />
&nbsp;&nbsp;&lt;ul&gt;<br />
&nbsp;&nbsp;&nbsp;&nbsp;&lt;li&gt;Sublist Item 1&lt;/li&gt;<br />
&nbsp;&nbsp;&nbsp;&nbsp;&lt;li&gt;Sublist Item 2&lt;/li&gt;<br />
&nbsp;&nbsp;&nbsp;&nbsp;&lt;ul&gt;<br />
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;li&gt;Subsublist Item 1&lt;/li&gt;<br />
&nbsp;&nbsp;&nbsp;&nbsp;&lt;/ul&gt;<br />
&nbsp;&nbsp;&nbsp;&nbsp;&lt;li&gt;Sublist Item 3&lt;/li&gt;<br />
&nbsp;&nbsp;&lt;/ul&gt;<br />
&nbsp;&nbsp;&lt;li&gt;List item 2&lt;/li&gt;<br />
&nbsp;&nbsp;&lt;li&gt;List Item 3&lt;/li&gt;<br />
&lt;/ul&gt;<br />

In XHTML, this is not valid (the w3 validator will complain about "document type does not allow element "ul" here; assuming missing "li" start-tag". The reason is that an nested <ul> belongs within an <li> tag. You might worry that this would put a higher level bullet on the sublist– it doesn’t. The key is you don’t close the <li> tag from the previous entry until after the sublist finishes. Compare the following. (note that both are syntactically correct XHTML)

Enjoy.