Introducing HTML5 markup - HTML5 and CSS3 - page 15

Now let's consider the <header> element. It represents the header of a
document, a section, or an article, typically containing headings and
other metadata about the section. You'll frequently have content that
you don't want to be part of the heading element itself but that doesn't
fit in with the following content. Examples would be subheadings,
author bylines, and publishing date information:

<h1>Articles</h1>
<article>
<header>
<h1>Main heading</h1>
<p>Some text</p>
</header>
<h2>Level 2 heading</h2>
<p>Some more text</p>
<h3>Level 3 heading</h3>
<p>A bit more text</p>
<h2>Another level 2 heading</h2>
<p>The last bit of text</p>
</article>
<article>
<header>
<h1>Main heading</h1>
<p>Some text</p>
</header>
<h2>Level 2 heading</h2>
<p>Some more text</p>
<h3>Level 3 heading</h3>
<p>A bit more text</p>
<h2>Another level 2 heading</h2>
<p>The last bit of text</p>
</article>

the <header> element does
not have any impact on
the document outline.
it's as if it's not there.

Common page elements
There are more new elements than <article> , <section> , <header> , and
<hgroup> . Let's look at some more pages from our set of typical web-
sites.