TCP refers to the transmission control protocol. It is a connection-oriented, reliable and byte stream-based transport layer communication protocol. Contact TCP and UDP, and UDP is also an important transport protocol. TCP provides functions such as overtime retransmission, discarding duplicate data, data verification, flow control, etc. to ensure that data can be transmitted from one end to the other.

1, which provides reliable data transmission in IP environment (the byte stream sent by one computer will be sent to other computers on the network without error, and when computer A receives the data packet, it will also send back the data packet to computer B, which will also generate some traffic), effective flow control, full duplex operation (data can be transmitted in both directions at the same time), multiplexing service, connection-oriented and end-to-end transmission;

2. Connection-oriented: You must establish a connection with the other party before formal communication. Open a connected channel for the sent data in advance, and then send the data, just like making a phone call.

3. Application protocols supported by 3.TCP: FTP file transfer, RLogin remote login, SMTP POP3 e-mail, NFS network file system, remote printing, remote execution, name server terminal server and other service types.