an endpoint of an inter-process communication flow across a computer network.
- Local socket address: Local IP address and port number
- Remote socket address: Only for established TCP sockets. As discussed in the client-server section below, this is necessary since a TCP server may serve several clients concurrently. The server creates one socket for each client, and these sockets share the same local socket address from the point of view of the TCP server.
- Protocol: A transport protocol (e.g., TCP, UDP, raw IP, or others). TCP port 53 and UDP port 53 are consequently different, distinct sockets.