<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>?