Social networks exist to sell you crap. The icky feeling you get when your friend starts to talk to you about Amway, or when you spot someone passing out business cards at a birthday party, is the entire driving force behind a site like Facebook.
Because their collection methods are kind of primitive, these sites have to coax you into doing as much of your social interaction as possible while logged in, so they can see it. It's as if an ad agency built a nationwide chain of pubs and night clubs in the hopes that people would spend all their time there, rigging the place with microphones and cameras to keep abreast of the latest trends (and staffing it, of course, with that Mormon bartender).
We're used to talking about how disturbing this in the context of privacy, but it's worth pointing out how weirdly unsocial it is, too. How are you supposed to feel at home when you know a place is full of one-way mirrors?
We have a name for the kind of person who collects a detailed, permanent dossier on everyone they interact with, with the intent of using it to manipulate others for personal advantage - we call that person a sociopath. And both Google and Facebook have gone deep into stalker territory with their attempts to track our every action.
section – Used for grouping together thematically-related content. Sounds like a div element, but its not. The div has no semantic meaning. Before replacing all your div’s with section elements, always ask yourself, “Is all of the content related?”
aside – Used for tangentially related content. Just because some content appears to the left or right of the main content isn’t enough reason to use the aside element. Ask yourself if the content within the aside can be removed without reducing the meaning of the main content. Pullquotes are an example of tangentially related content.
header – There is a crucial difference between the header element and the general accepted usage of header (or masthead). There’s usually only one header or ‘masthead’ in a page. In HTML5 you can have as many as you want. The spec defines it as “a group of introductory or navigational aids”. You can use a header in any section on your site. In fact, you probably should use a header within most of your sections. The spec describes the section element as “a thematic grouping of content, typically with a heading.”
nav – Intended for major navigation information. A group of links grouped together isn’t enough reason to use the nav element. Site-wide navigation, on the other hand belongs in a nav element.
footer – Sounds like its a description of the position, but its not. Footer elements contain information about it’s containing element: who wrote it, copyright, links to related content, etc. Whereas we usually have one footer for an entire document, HTML5 allows us to also have footer within sections.
Curiosity was framed, ignorance killed the cat.