TCP

The Transmission Control Protocol (TCP) is how TCP/IP does connection-oriented communication. TCP is by far the most common type of session on a typical TCP/IP network. For example two computers, one Server and second one Client. One computer (Server) runs a Web server and the other (Client) runs a Web browser. When you enter a computer's address in the browser running on Client, it sends a single SYN (synchronize) packet to the Web server. If Server gets that packet, it sends back a single SYN, ACK (synchronize, acknowledge) packet. Client then sends Server a single ACK packet, and immediately requests that Server begin sending the Web page.

Once Server completes sending the Web page, it sends a FIN (finished) packet. Client responds with an RST, ACK (reset, acknowledge) packet and the session is over.

Most TCP/IP applications use TCP because connection-oriented sessions are designed to check for errors. If a receiving computer detects a missing packet, it just asks for a repeat as needed.