Winsock API Specifications

The Winsock 2 Specifications (in Microsoft Word format) are must-have documents for the Winsock programmer as they are the final word on what Winsock is supposed to do. You can also access this info through the MSDN Library.

Winsock Software Development Kit

The Winsock SDK is part of the Windows Platform SDK these days. All Windows development tools since the late 90's have some kind of Winsock support built in. You will only need this if you have a really old development tool, or if you need cutting-edge features that haven't yet made it into the mainstream development tools.