The two most common types of lists are ordered and unordered.
<ol>
<li>Apples</li>
<li>Bananas</li>
<li>Cherries</li>
</ol>
and
<ul>
<li>Apples</li>
<li>Bananas</li>
<li>Cherries</li>
</ul>
Starting each element on its own line and indenting child elements makes the code much easer to scan at a glance, and also makes it easier to spot missing closing tags.
Would you rather read this:
<body><h1>
Hello! Here are some of my favorite fruits:
</h1>
<ol><li>Apples</li> <li>Bananas</li>
<li>Cherries</li></ol>
</body>
or this:
<body>
<h1>Hello! Here are some of my favorite fruits:</h1>
<ol>
<li>Apples</li>
<li>Bananas</li>
<li>Cherries</li>
</ol>
</body>
I thought so. :-)