Over the course of less than a decade, Facebook has morphed from a small, niche networking site for mostly Ivy League college students into a publicly traded company estimated to be worth at least $50 billion. Facebook boasts that it is free to join and always will be, so where’s the money coming from to service 1 billion subscribers? Just like its fellow tech titan entirely from advertising. Facebook does not have a diverse array of hot new gadgets, a countrywide network of brick-and-mortar retail outlets, or a full inventory of software for sales; instead, it has your personal information, and the information of hundreds of millions of others with Facebook accounts.