TCP (Transmission Control Protocol)
used along with the Internet Protocol (IP) to transmit data as packets
between computers over the network. While IP takes care of the actual
packet delivery, TCP keeps track of the individual packets that the
communication (e.g. requested a web page file) is divided into, and,
when all packets have arrived at their destination, it reassembles them
to re-form the complete file.
TCP is a
connection-oriented protocol, which means that a connection is
established between the two end-points and is maintained until the data
has been successfully exchanged between the communicating applications.