Love it or hate it, Facebook is now the undisputed king of online socializing. Since its inception in 2004 as a Harvard University-based social experiment, the website has recruited 500 million users in 95 countries -- and in doing so, fundamentally changed the way friends, casual acquaintances and sometimes total strangers interact with one another. For the younger generations, it's becoming hard to remember a time before wall posting, Facebook event RSVP-ing and photo tagging were part of our everyday lexicon, and even for the rest of us, its become a major center for news consumption and social activism -- from advocating same-sex marriage to Betty White's "Saturday Night Live" gig -- and got us to stay in touch with our high school friends, whether we wanted to or not.
