An Internet socket (or commonly, a socket or network socket), is a communication end-point unique to a machine communicating on an Internet Protocol-based network, such as the Internet. (See RFC 147 for the original definition of socket as it relates to the ARPA network in 1971.)

Internet sockets are composed of an IP address and a transport protocol port number. Operating systems associate sockets with a running process or processes (which use the socket to send and receive data over the network), and a transport protocol (i.e. TCP or UDP) with which the process(es) communicate to the remote host.

Modern, Internet-enabled operating systems generally provide an implementation of the Berkeley Sockets API or Berkeley Sockets Layer, first introduced in 1983. Other socket API implementations exist, such as the STREAMS-based Transport Layer Interface (TLI).

See also

• Internet Protocol
• Internet protocol suite
• Packet
• Raw socket
• TCP and UDP port numbers
• Unix domain socket for a similar abstraction for local communication
• Named pipe for one-way communication

Inter-process communication