The importance of HTML5 sectioning elements by Heydon Pickering
A good explanation of HTML5’s sectioning content and outline algorithm.
Tags: outline
HTML5 And The Document Outlining Algorithm - Smashing Magazine
A brave attempt to explain the new outline algorithm in HTML (although it inaccurately states that no browsers have support for it—Firefox shipped with it a while back).
You can safely skip the comments: most of them are discouraging, ignorant, and frankly, just plain stupid.
Document Outlines | HTML5 Doctor
Mike takes on the very tricky task of explaining the new outline algorithm—definitely one of the hardest features of HTML5 to explain, in my opinion.
HTML 5 Outliner
A very handy tool to help you check the outline algorithm in HTML5.