My definition of the aside element would be "information either unrelated or loosely related to the main content of a page should go in aside tags" – however, that is not W3C's definition. They write: "The aside element represents content that is tangentially related to the content that forms the main textual flow of a document." *
That confuses me. Anyone who speaks English knows what the word "aside" means. Anyone should be able to more or less understand what the aside element does without having read a word on the subject. After trying to penetrate W3C's definition I'm not so sure. It bewilders more than it enlightens – frankly, it's pedantic nonsense.
The OED defines aside as "to one side; out of the way". ** That I get.
W3C goes on to say: "The element can be used for typographical effects like pull quotes or sidebars, for advertising, for groups of nav elements, and for other content that is considered separate from the main content of the page." *
That's a little better. I don't remember ever using "pull quotes", "sidebars" or "groups of nav elements" and I doubt I ever will. You never know, but I doubt it. On the other hand where to put advertising is a real, everyday problem I and tens of thousands of other web designers do have.
For better SEO I want to be able to separate ads from content – to, if you will, "put them aside". The search engines should know what I think is and isn't significant. The aside element gives me the means to include something in a page that is not important to the meaning of the page. Ads are not related – tangentially or otherwise – to anything more than me needing to pay the rent. They go in aside tags.
I genuinely appreciate the monumental effort W3C is putting into rewriting HTML, but I do wish they would write better English. "Anyone who thinks clearly can write clearly, about anything." William Zinsser, On Writing Well ***
If someone from W3C ever reads this please buy Zinsser's book and read it. In the mean time the rest of us will just have to forge ahead as best we can. Unfortunately there is a lot more of the same where that came from.
*** William Zinsser, On Writing Well, page 149 – See Zinsser's book on Amazon.