In Pictures: Facebook turns 10 - A look back at th...
Facebook invites developers to build apps
Facebook Platform was launched in May 2007 and invited third-party developers to build apps that run on Facebook. This led to the growth of social gaming company Zynga, for example, which at one point derived 80% of its revenue from Facebook apps like FarmVille and Texas HoldEm Poker.
In Pictures: Facebook turns 10 - A look back at the milestones