1 <p>The to-do list will be even more useful if it includes the cat’s favorite dishes. Therefore, it would be good to add a nested list or sublist to the item “Feed the cat”.</p>

2 <p>The &lt;ol&gt; and &lt;ul&gt; tags can be nested within each other in order to create multi-level lists. There are no restrictions on the number of levels in lists.</p>

3 <p>First, you need to create a first-level list, and then you need to add another list between the &lt;li&gt; and &lt;/li&gt; tags for this list. In this case, you must carefully close all of the tags in the proper order:</p>

4 &lt;ol&gt; &lt;li&gt;1 &lt;ul&gt; &lt;li&gt;1.1&lt;/li&gt; &lt;li&gt;1.2&lt;/li&gt; &lt;/ul&gt; &lt;/li&gt; &lt;li&gt;2&lt;/li&gt; &lt;/ol&gt;<p>And here is an example of an error when the sublist &lt;ul&gt; is nested between &lt;li&gt; tags and not inside them:</p>

5 &lt;ol&gt; &lt;li&gt;1&lt;/li&gt; &lt;ul&gt; &lt;li&gt;1.1&lt;/li&gt; &lt;li&gt;1.2&lt;/li&gt; &lt;/ul&gt; &lt;li&gt;2&lt;/li&gt; &lt;/ol&gt;