1. TCP is a communications protocol used along with the Internet Protocol (IP) to send data in the form of individual units (called packets) between computers over the Internet. While the IP protocol handles the actual delivery of the data, TCP keeps track of the packets that a message is divided into for efficient routing through the Internet. For example, when a Web page downloads from a Web server, the TCP program layer in that server divides the file into packets, numbers the packets, and then forwards them individually to the IP program layer. Although each packet has the same destination IP address, it may get routed differently through the network. At the other end of the transmission, TCP reassembles the individual packets and waits until they have all arrived to forward them as a single file.