HTML5 - Correct usage of the <article> tag

Question

Reading an article on the <article> tag on HTML5, I really think my biggest confusion is in the first question of this section:

Using <article> gives more semantic meaning to the content. By contrast <section> is only a block of related content, and <div> is only a block of content... To decide which of these three elements is appropriate, choose the first suitable option:

1. Would the content would make sense on its own in a feed reader? If so, use <article>.
2. Is the content related? If so, use <section>.
3. Finally, if there’s no semantic relationship, use <div>.

So I guess my question is really: What types of content belong in a feed reader?

Answer 1

The spec answers this quite clearly:

The article element represents a self-contained composition in a document, page, application, or site and that is, in principle, 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.

see: http://dev.w3.org/html5/spec/Overview.html#the-article-element