Legitimate line breaks can occur in the likes of addresses or poetry — when they are a meaningful part of the content. They should not be used for purely stylistic reasons, such as replicating the look of a paragraph (when a
p element would be appropriate).
br has no content and therefore does not warrant a closing tag.
<p>There was a loud lady named Noa,<br>
Who stumbled on a four-meter boa;<br>
Around her neck it wrapped,<br>
Until her vocal chords snapped,<br>
And now the volume around town is much lower.</p>