About Windows API
The Windows API comes in several difference forms today. The core of the Windows API (WinAPI) is programmed using the C/C++ programming language. The WinAPI is the most powerful because it exposes all the features of every new Windows operating system version.
The next API is a set of C++ classes, the Microsoft Foundation Classes (MFC), that wrap some of the complexity of the core Windows API. It loses some access to the latest operating system abilities until updated by Microsoft. But MFC was still complex and Microsoft needed a newer API that was easier to program with. See Analog Clock, Tic-Tac-Toe and Hex Dump for MFC examples.
Finally, Microsoft came out with a more-powerful-than-MFC API called the .NET Framework. More powerful and easier to use by utililizing higher generation languages like C# and VB.NET and having a more extensive library. The downside to this API is that the .NET Framework must be installed on each machine except Windows Vista and later versions. See Analog Clock, Tic-Tac-Toe, HexDump, Image Viewer and System Info for .NET examples.
MFC and the .NET Framework both, for the most part, work on top of the core Windows API with a goal to simplify the core API and speed the development cycle.