The TCP/IP protocol suite form the backbone of the global Internet. The original Windows Sockets specification (version 1.1) addressed only TCP/IP protocols, and still has a few IP-specific peculiarities.
Two basic types of transport services are offered: unreliable datagrams (UDP), and reliable connection-oriented byte streams (TCP). In addition, a raw socket is optionally supported. Raw sockets allow an application to communicate via protocols other than TCP and UDP such as ICMP.