role article

A section of a page that consists of a composition that forms an independent part of a document, page, or site.

Setting an ARIA role and/or aria-* attribute that matches the default implicit ARIA semantics is unnecessary and is not recommended as these properties are already set by the browser.

<article>
  <h1>My first article</h1>
  <p>Lorem ipsum...</p>
</article>

You would use role=article on non-semantic elements (not recommended, invalid)

<div role="article">
  <h1>My first article</h1>
  <p>Lorem ipsum...</p>
</div>

W3C Entry for role=article