The social network that began 2009 with 150 million members signed up number 200 million in April. By September, it had amassed 300 million — an average growth rate this year of about 550,000 new members a day.
And with that growth came new demographics: 71% of Facebook users now live outside the U.S. and many of them are older than the site's original college-age demographic. But even more surprising than Facebook's exponential popularity was the announcement that, for the first time ever, the company was making money.
Facebook is a private company estimated to be worth about $15 billion. Not too shabby for a start-up run by a 25-year-old Harvard dropout.