Facebook hasn't had a year this eventful since it launched in 2004. Let's look at the past six months: The social network founded in Mark Zuckberg's Harvard dorm room went public in May, raising $16 billion, which made it the the third-largest initial public offering in U.S. history. The company's stock price stalled, then plummeted from its IPO price of $38 to below $20 a share. The company, its founder, and many investors lost billions of dollars. More than 40 lawsuits were filed against Facebook and its underwriters, Morgan Stanley, JP Morgan, and Goldman Sachs, for withholding adjusted financial information. 

On the brighter side of things, Facebook bought the hottest new app, Instagram, for $1 billion, launched its own mobile camera app, and improved the speed and usability of its iOS and Android apps. It also opened its own app store. And then, to top it all off, on October 4 it announced that there are now more than one billion people actively using Facebook. 

Though it's only been around for eight years, it feels as if Facebook has been around as long as the Internet itself. That said, you may think you know everything there is to know about the world's largest social network. But did you know that its music app, launched in September 2011, has been used to play 62.6 million songs 22 billion times? No? Cool. Keep reading.