What it is
<main>, <nav>, <article> and a single <h1> are not decoration. They are the only reliable signal separating the page's subject from its furniture.
Heading levels also carry the document outline — which sections exist, and which belong inside which.
Why an agent cares
Without landmarks, a text extractor takes everything, so your cookie notice, your nav and your footer arrive weighted the same as your product description.
Multiple <h1> elements make the page's actual subject ambiguous at exactly the moment something is trying to work out what it's about.
How to fix it
- Exactly one
<h1>per page, describing that page. - Wrap the real content in
<main>; keep navigation inside<nav>. - Use heading levels in order — don't jump h2 to h4 for the size.
How we test it
We count <h1> elements, all headings, and check for <main> and <nav>.