This is the Windows application programming interface (API) for developing 32-bit applications. It has been used for Windows 95, Windows 98, Windows NT, and newer Windows operating systems. This means that if you use Windows 95 or later, you can run 32-bit applications on your computer. Win32 is a term that is important to programmers, but is not crucial for the average user to know. Just know that if you have Windows 95 or later, you can run Win32 applications. If you want to learn more about Win32, including a bunch of technical jargon, you can visit Microsoft's Developer Website for more information.