Connection-oriented communications in AF_INET and AF_INET6

Sockets which communicate with each other are connected via an assignment. An assignment in the Internet domain consists of a local address and local port number and a remote address and remote port number.

<local address, local port, foreign address, foreign port>

When setting up a socket, you must initially specify both address-pairs. The bind() call specifies the local half of the assignment:

<local address, local port>

The calls of the connect() and accept() functions described below, complete the socket assignment during connection setup.
The connection setup between two sockets is generally asymmetric, with one socket assuming the role of the client and the other the role of the server.