Facebook’s Bold, Compelling and Scary Engine of Discovery: The Inside Story of Graph Search

“we can answer a set of questions that no one else can really answer. All those other services are indexing primarily public information, and stuff in Facebook isn’t out there in the world — it’s stuff that people share. There’s no real way to cut through the contents of what people are sharing, to fulfill big human needs about discovery, to find people you wouldn’t otherwise be connected with. And we thought we should do something about that. We’re the only service in the world that can do that.”
“Let’s say we’re trying to find engineers at Google who are friends of engineers at Facebook.” He typed in the query and found, not surprisingly, that there were lots of people who met those criteria.