by kleinbl00

It took just three years for FIS to evolve from basic beginnings into an all-seeing set of algorithms that monitors every photo posted to the network, every status update– indeed, every click made by every one of the 800 million users. There are more than 25 billion of these "read and write actions" every day. At peak activity the system checks 650,000 actions a second.

"It's a big challenge," says Jim Larus, a Microsoft researcher in Redmond, Washington, who studies large networks. The only network bigger, Larus suspects, is the web itself. That makes Facebook's defence system one of the largest in existence.