Google is kicking off I/O 2015, its big developer showcase for this year, with one very round and large number: a billion users. The Mountain View company now has over a billion users each for its core services of search, Chrome, Android, and YouTube. Gmail is only a hair's breadth away, with a total of 900 million active users each month. Sundar Pichai opened the keynote presentation with these numbers and observed that everything Google has ever done has been with the goal of the widest possible accessibility. "Each of these products work," he says, "at scale for everyone in the world." Well, they work for the first billion people in the world, at least.