The team in charge of tracking Facebook’s growth works on the second floor of Building 17. Most days, the offices are like anywhere else at Facebook: whiteboards, toys on desks, shorts and flip-flops, pretty low-key. Around noon on Sept. 14, the second floor was packed. In one of the common areas, a giant screen showed the number of active Facebook users worldwide. About 100 people, including Mark Zuckerberg and his top lieutenants, watched the numbers run up by about a thousand users per minute: 999,980,000 … 999,990,000 … 1,000,000,000. The counter paused for a moment when it rounded 10 digits, as if to emphasize the point: 1 billion users.
The celebration was less exuberant than one might imagine given that Facebook had just officially registered one-seventh of earth’s population. Zuckerberg had thought about doing the whole balloons-and-visit-from-Ryan-Seacrest thing when they located lucky user No. 1,000,000,000. The problem, though, was that the occasion was really more of a notional event, like when the United Nations announces the world’s population. Facebook’s vast array of computers handles so many users doing so many things, the best they can do is make a statistical calculation. After a few minutes of hoots, high-fives, and good cheer, Zuckerberg and his employees did what they usually do after major achievements: They went back to work.