The team in charge of tracking Facebook’s (FB) 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.

Read Here – Businessweek