In computer networking, a socket* is an endpoint of a bidirectional inter-process communication flow across an Internet Protocol-based computer network, such as the Internet.
An internet socket address is the combination of an IP address (the location of the computer) and a port (which is mapped to the application program process) into a single identity, much like one end of a telephone connection is the combination of a phone number and a particular extension. It is primarily used in the Transport Layer.
An example IPv4 socket appears as:
An example IPv6 socket appears as:
[fe80::1]:80 (Note the brackets)
The term is believed to have originated with the Berkeley Sockets API for Unix ca. 1983.