Sectioning elements divide a page into meaningful regions. Several of them map to ARIA landmarks — named regions that assistive tech lets users jump between, like a table of contents for the page.
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Screen reader users can press a key to list landmarks and jump straight to <main>, skipping repeated headers and nav. This is a major efficiency gain — the semantic tags provide it automatically, no ARIA needed.
<article> — content that makes sense on its own and could be syndicated: a blog post, a product card, a comment.<section> — a thematic grouping within a document, normally with its own heading. Not standalone.<article>
<h1>Blog post title</h1>
<section><h2>Introduction</h2>...</section>
<section><h2>Conclusion</h2>...</section>
</article>
Rule of thumb: if it could stand alone, it's an <article>; if it's just a labeled chunk of a larger whole, it's a <section>. Don't use <section> purely as a styling wrapper — that's what <div> is for.
Using the right sectioning elements gives you free, robust landmarks for keyboard/screen-reader navigation and a clear document outline — improving accessibility and SEO without any extra ARIA attributes.