Of course, all of the networking sites had profiles and friends. What was Facebook doing that Friendster, Google, and MySpace were not? Nothing technical, to be sure; rather, it unmistakably defined itself as the place to be. The key to this was its campus origins. While the others obliged users to find their cohort in the great mass of undifferentiated humanity, Facebook re-created an existing and relatively bounded social reality of colleges, within and among which actual connections already existed. Everyone at Harvard knew at least someone on several of the campuses across which Facebook's network was proliferating. The original university facebook goal of facilitating socialization was thus served by this thing that was student made, a fact that only lent it more social credibility. So Facebook was actually providing not something new but an enhanced representation of an existing social reality. The networks, so-called, were there already: Facebook simply made them visible, graphically manifest, and easier to keep track of.

Tim Wu, The Attention Merchants, loc. 996