Question

Is the article tag of HTML5 only to use in blogs? Is it only for blog articles? Is it not to use for the content section of website, which is not a blog?

Generally I use

<div id="content">
<h2> title </h2>
<p> content </p>
</div>

Should I replace div with article

<article id="content">
<h2> title </h2>
<p> content </p>
</article>

or

<div id="content">
<article>
<h2> title </h2>
<p> content </p>
</article>
</div>

Answer 1

From the spec:

The article element represents a
component of a page that consists of a
self-contained composition in a
document, page, application, or site
and that is intended to be
independently distributable or
reusable, e.g. in syndication. This
could be a forum post, a magazine or
newspaper article, a blog entry, a
user-submitted comment, an interactive
widget or gadget, or any other
independent item of content.

So I guess it is quite dependant on what #content contains. If it would only contain that specific article (or stuff related to that article, like comments nested as further articles), you do not need the div.

My favourite resource about this – HTML5Doctor