IP 
Internet Protocol 
The method by which data is sent from one computer to another on the Internet. IP is combined with the Transmission Control Protocol (TCP) to ensure that data sent between computers does not go astray. Each computer on the Internet has at least one unique IP address. When you send or receive data--e-mail, for example--the message is divided into data packets, each of which contains the sender's and the receiver's IP addresses. The packets are sent to an Internet gateway computer, then through various routes to their destination. TCP reassembles the packets correctly once they arrive.