A socket is an endpoint for communication able to be named and addressed in a network. From the perspective of the application program, it is a resource allocated by the address space; it is represented by an integer called the socket descriptor.
The socket interface was designed to provide applications a network interface that hides the details of the physical network. The interface is differentiated by the different services provided: Stream, datagram, and raw sockets. Each interface defines a separate service available to applications.
The MVS™ socket APIs provide a standard interface using the transport and internetwork layer interfaces of TCP/IP. These APIs support three socket types: stream, datagram, and raw. Stream and datagram socket types interface with the transport layer protocols; raw socket types interface with the network layer protocols. Choose the most appropriate interface for your application.