Big websites usually maintain their own "data centers," banks of tens or even hundreds of thousands of servers, all passing data back and forth to field users' requests. Like any big, decentralized network, data centers are prone to congestion: Packets of data arriving at the same router at the same time are put in a queue, and if the queues get too long, packets can be delayed. Researchers have designed a new network-management system that, in experiments, reduced the average queue length of routers in a Facebook data center by 99.6 percent -- virtually doing away with queues.

Source: No-wait data centers: Data-transmission delays across server farms can be reducd by 99. 6 percent