Store applications are built and execute against a new runtime called Windows Runtime (WinRT) that is not present on previous Windows versions. WinRT is built upon the well-established COM technology (with some WinRT-specific enhancements, such as the use of metadata). This means WinRT is entirely native (no .NET CLR anywhere), making C++ a natural and performant choice for targeting this runtime.
WinRT provides a set of services, on which apps can be built. The relationship between the WinRT and applications can be represented by the following diagram:
WinRT APIs have the following characteristics: