TCP/IP - Transmission Control Protocol/Internet Protocol (currently in revision 4, known as IPv4, and sometimes called 4bone) - is a communication language that is used for transmitting data over networks. It is the main protocol for the Internet. TCP/IP is a set of instructions that describes how packets of information are sent across multiple networks. The TCP part deals with the verifying delivery of the packets. The IP part refers to the moving of data packets between nodes.