Transmission Control Protocol (TCP)
TCP functions at the transport layer of the OSI model and is a connection-oriented protocol that uses IP as its network protocol. Being connection-oriented means that TCP establishes a mutually acknowledged session between two hosts before communication takes place. TCP provides reliability to IP communications. Specifically, TCP adds features such as flow control, sequencing, and error detection and correction. For this reason, higher-level applications that need guaranteed delivery use TCP rather than its lightweight and connectionless brethren, the User Datagram Protocol (UDP).