Three-way handshake

The Transmission Control Protocol (TCP) is one of the main of the . It originated in the initial network implementation in which it complemented the (IP). Therefore, the entire suite is commonly referred to as TCP/IP. TCP provides reliable, ordered, and error-checked delivery of a stream of octets between applications running on hosts communicating by an IP network. Major Internet applications such as the World Wide Web, email, remote administration, and file transfer rely on TCP. Applications that do not require reliable data stream service may use the (UDP), which provides a connectionless datagram service that emphasizes reduced latency over reliability.

During May 1974, the Institute of Electrical and Electronic Engineers (IEEE) published a paper titled A Protocol for Packet Network Intercommunication. The paper's authors, Vint Cerf and Bob Kahn, described an internetworking protocol for sharing resources using packet-switching among the nodes. A central control component of this model was the Transmission Control Program that incorporated both connection-oriented links and datagram services between hosts. The monolithic Transmission Control Program was later divided into a modular architecture consisting of the Transmission Control Protocol at the connection-oriented layer and the Internet Protocol at the internetworking (datagram) layer. The model became known informally as TCP/IP, although formally it was henceforth termed the Internet Protocol Suite.

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