TCP/IP 
Transmission Control Protocol/Internet Protocol 
The basic communication protocol used on the Internet. TCP/IP actually consists of two protocols, which were developed by Bob Kahn and Vinton Cerf in 1973 while under contract to the U.S. government's Defense Advanced Research Projects Agency. TCP/IP formed the basis of the ARPANET, which eventually grew into the Internet. IP determines how data is formatted into smaller chunks, called packets, and ensures that those packets are addressed correctly to reach the right destination. TCP is responsible for establishing a connection between the client computer and the server and transmitting the data packets. TCP/IP is built into every common modern operating system.