What is TCP?

Transmission Control Protocol (TCP) is a transport layer protocol used to create a connection between applications so that they can exchange data over a communication network.

Key features

• TCP provides a process for communication. Port numbers are appended in the header of the packet to enable this.

• A three-way handshaking process takes place to open a connection in TCP; hence, it is called a connection-oriented protocol.

• A packet (called a segment in case of TCP) contains a checksum field used for error control.

• TCP prevents the sender from sending in more data than the receiver can handle with the window size provided by the receiver.

• It guarantees the reliable delivery of segments. Incase of segment loss or corruption, segments are re-transmitted.

• It reassembles the packets in the correct order at the receiver side.

• It uses a congestion avoidance algorithm to avoid the network from being congested.

TCP segment

The TCP segment consists of a header and data. The following illustration goes over its structure:

Applications that use TCP

TCP is used where reliable in-order delivery of packets is needed. Such applications include:

• Web surfing

• Sending and receiving emails