The Win32 API (also called the Windows API) is the original platform for native C/C++ Windows applications that require direct access to Windows and hardware. It provides a first-class development experience without depending on a managed runtime environment like.NET and WinRT (for UWP apps for Windows 10).

WINAPI is a macro that evaluates to __stdcall, a Microsoft-specific keyword that specifies a calling convention where the callee cleans the stack. The function's caller and callee need to agree on a calling convention to avoid corrupting the stack.

Microsoft Foundation Class Library (MFC) wrapped Windows API functionality in C++ classes, and thus allows a more object-oriented way to interact with the API.