the social sites that arrived in the 2000s did not create the social web, but they did structure it. This is really, really significant. In large part, they made sharing on the Internet an act of publishing (!), with all the attendant changes that come with that switch. Publishing social interactions makes them more visible, searchable, and adds a lot of metadata to your simple link or photo post. There are some great things about this, but social networks also give a novel, permanent identity to your online persona. Your taste can be monetized, by you or (much more likely) the service itself