Note: The following is an excerpt from the official IETF RFC. It is provided here as a convenience and is not authoritative. Refer to the original document as the authoritative reference.
Introduction
A socket is defined to be the unique identification to or from which
information is transmitted in the network. The socket is specified as a 32
bit number with even sockets identifying receiving sockets and odd sockets
identifying sending sockets. A socket is also identified by the host in
which the sending or receiving processor is located.