Winsock or Windows sockets denotes a set of utilities to access network components under Microsoft Windows.

Winsock added Windows to the Internet protocol suite and is responsible for connecting the PC to the Internet. It is used by programs to access the Internet Protocol (IP) to the network. The program calls for certain functions in the library winsock.dll (or from Windows 95/NT wsock32.dll ).


When a program wants to communicate ( for example, a web browser) via the network ( for example, a Web server contacted ), there is the request to Winsock, which then attempts to establish the connection. Winsock reports back to the calling program, whether the connection succeeded or failed. If a connection can be made ​​, can use other Winsock function calls using this connection to exchange data over the network (eg loading of web pages).

By using the Winsock API, it is in principle possible to write IP -use programs that are source-code compatible between Windows and POSIX operating systems, which since Winsock 2.0, other than the protocols of the Internet protocol suite are possible, such as IPX.


Winsock was developed in 1992 by Microsoft. For this, all functions were taken over by the operating systems UNIX and BSD practical. Previously, one had to rely on third-party implementations, such as the popular shareware from Peter Tattam.