<br> doesn't have a closing tag because it's an empty tag. Empty tags don't have content, but they can still help structure a page.

<body>
<h1>My favorite things</h1>
<p>
Raindrops on roses<br>
Whiskers on kittens
</p>
<p>
Bright copper kettles<br>
Warm woolen mittens
</p>
</body>
</html>

]]>

Exactly! We can use as many <br> tags as we want, but we never have to close them.

Maybe a closing tag is not needed for <br>?