A transport-layer protocol in the TCP suite needs both the IP address
and the port number, at each end, to make a connection. The
combination of an IP address and a port number is called a socket
address.
The client socket address defines the client process uniquely just as
the …
Process to process delivery (transport layer communication) needs two identifiers, one is IP address and the other is port number at each end to make a connection.
Socket address is the combinations of IP address and port number as shown in the figure.