The term *native desktop client applicaton* refers to a C or C++ windowed application that uses the original native [Windows C APIs and/or COM APIs](/windows/desktop/apiindex/windows-api-list) to access the operating system. Those APIs are themselves written mostly in C. When creating this kind of application, you have the choice of programming directly against a C-style message loop that processes operating system events, or using *Microsoft Foundation Classes* (MFC), a C++ library that wraps Win32 in a way that is somewhat object-oriented. Neither approach is considered "modern" compared to the Universal Windows Platform (see below), but both are still totally supported and have millions of lines of code running in the world today. A Win32 application that runs in a window requires the developer to work explicitly with Windows messages inside a Windows procedure function. Despite the name, a Win32 application can be compiled as a 32-bit (x86) or 64-bit (x64) binary. In the Visual Studio IDE, the terms x86 and Win32 are synonymous.