<hgroup>
Groups a heading with its subtitle, tagline, or eyebrow paragraphs as one unit.
Baseline: Widely available · Sectioning & landmarks
When to use it
When a heading has a subtitle that belongs to it — title plus tagline, version plus codename.
When not to
Only p elements may accompany the single heading inside; a second heading level does not belong in an hgroup.
Example
The Semantic HTML Vocabulary
A self-demonstrating field guide
<hgroup>
<h2>The Semantic HTML Vocabulary</h2>
<p>A self-demonstrating field guide</p>
</hgroup>