<header>
Introductory content for the page or for any article/section — headings, bylines, intro nav.
Baseline: Widely available · Sectioning & landmarks
When to use it
As the page banner (direct child of body, one only) or scoped inside each article/section for its own heading block.
When not to
Don't treat it as a styling wrapper; it must introduce the region it belongs to.
Example
Version 2.4.0
Released
<article>
<header>
<h2>Version 2.4.0</h2>
<p>Released <time datetime='2026-07-20'>July 20, 2026</time></p>
</header>
</article>