A self-clocking heuristic that aggregates outgoing data to improve throughput and avoid silly window syndrome.

Put a different way, the Nagle algorithm is the process by which, on a TCP connection, a host holds back further transmissions of interactive user data until it has recieved acknowledgement from the server. In this way, many small segments with little data are avoided, so-called tinygrams. Usually this isn't a problem on LANs, but over the big ole' WAN you're using right now, lots of tiny segments is a bad thing.