<figcaption>
The caption of a figure.
Baseline: Widely available · Grouping content
When to use it
First or last child of figure; also the right home for a blockquote's attribution.
When not to
Only valid inside figure; it does not replace an image's alt text.
Example
Practice makes perfect.
<figure>
<blockquote><p>Practice makes perfect.</p></blockquote>
<figcaption>— an English proverb</figcaption>
</figure>