Every month, over a billion people open their phones and fire up Google Maps. Its original function—offering driving directions, with real-time traffic tracking—was disruptive enough in 2008, when most people had to pay $10 a month for traffic data. But since that time, it’s become a global business directory, a transit timetable, crowdedness monitor, a Street View miracle—and now, in its newest release, an augmented-reality viewer of the cityscape around you. The question is: How is Google doing it, and why is it free? Meet the man who runs Google’s entire Geo division.