FB's chief avenue to success was that they turned the chicken-and-egg problem of social networks (they are only helpful when lots of people your know are on the

FB's chief avenue to success was that they turned the chicken-and-egg problem of social networks (they are only helpful when lots of people your know are on the same network) into a shining example of the strength of the network effect. They did so by limiting signups to a single campus at first. Then they grew by expanding to specific campuses only. They made it so that facebook became the network for the students on each of those campuses to be on, yet kept the allure up by being exclusive. By the time they opened up to the wider public, the brand was super strong and entrenched. Also, facebook had a huge amount of money to throw at marketing. That shouldn't be forgotten. They essentially bought success by spending that money, when lots of other social networks never were able to do so.