The Windows API (Application Programming Interface) has come to be commonly known or refered to as Win32. If you want to create a program that would work in a Windows environment, you would need to have something that is compatible with Win32.

It has been used for Windows 95, Windows 98, Windows NT, and newer Windows operating systems. Developer support is available in the form of a software development kit, Microsoft Windows SDK, providing documentation and tools needed to build software based on the Windows API and associated Windows interfaces.

The Windows API (Win32) is focused mainly on the programming language C in that its exposed functions and data structures are described in that language in recent versions of its documentation. However, the API may be used by any programming language compiler or assembler able to handle the (well-defined) low-level data structures along with the prescribed calling conventions for calls and callbacks.