Friendster and MySpace were the pioneers of social networks, but who truly gave them the boost needed to start and get to where they are today, was Facebook back in 2004.
Then we know the story, some of which were once popular, now no longer resemble anything like what they were, or operation, or in popularity. The only one that survives and will continue for a long time is Facebook.
Then come those phenomena we do not understand the reason for its rapid success and we have several examples and to name a few: Pinterest and Instagram.
Twitter is another phenomenon, that while not a pure social network and serves as a link to communicate many people and create friendship, their greatest virtue is the information offered.
People of Silverpop conducted a study on the growth in terms of users of 20 of the top social networks.
That study was turned into an infographic that starts with a bar chart where you can see the social networks and the number of users of each.
Then divide networks like clubs and the club have 100 million users, the club's rising stars, the stable club, the club of child prodigies and finally the club being "cooling".