<section> marks sections
The section element is new to HTML5 and marks a section of a document.
<!DOCTYPE HTML>
<html>
<head>
<title>Example</title>
<style>
section { background: grey; color: white; }
</style>
</head>
<body>
<section>
<hgroup>
<h1>H1</h1>
<h2>H2</h2>
</hgroup>
<section>
<h1>H1 of section</h1>
<p>This is a paragraph.</p>
<section>
<h1>H1 in sub section</h1>
<p>This is a paragraph.</p>
</section>
</section>
</section>
<h1>H1 outside section</h1>
<p>This is a pargraph.</p>
<h2>H2</h2>
</body>
</html>