Socket

SOCKET :For computers to communicate over the Internet, each computer, client or server, must utilize a standard set of protocols called TCP/IP. This suite of protocols is referred to as a TCP/IP stack or socket.    
There are numerous versions of TCP/IP stack available, for every target platform and operating system (UNIX, PC, Macintosh, handheld devices, etc.). The TCP/IP stack,is composed of five layers: application, transport, Internet,data link, and physical.