From late 2006 to early 2009, I was privileged to hold a variety of management positions in Facebook Engineering, ranging from manager of various teams to director of engineering. During that time, the engineering department grew from about 30 to around 200 engineers. It was an era that roughly spanned the launch of News Feed, Facebook Platform (the first F8 conference), the launch of our self-serve advertising system (now a major contributor to our positive cash-flow), internationalization of the site, and Facebook Connect. We went from being a niche college social network with less than 10M users in 2006 to a global phenomenon with over 250M users by early 2009. It was a period of time during which the company grew from being a small startup (under 100 employees) to a medium-sized company (800+ employees).

Source: Engineering Management