Milestones in social networking over the past decade:
2002 _ Friendster launches and becomes a social networking force until MySpace and the more buttoned-up LinkedIn hit the scene in 2003 and slowly gain more traction.
2004 _ Facebook begins to become a staple of communication for college students. The service opens up to high schoolers in 2005, corporate networks in 2006 and eventually becomes a worldwide phenomenon.
2005 _ YouTube, an online video hosting site, launches.
2006 _ Twitter, a "microblogging site" that allows 140-character posts, begins and, by decade's end, becomes one of the fastest-growing social networking sites.
(Source: D.M. Boyd & N.B. Ellison, Journal of Computer-Mediated Communication)