Microsoft released the first public beta build of Windows 8 at the Build conference on September 13, 2011. The new OS tried to address almost every problem that Windows had by introducing features such as a responsive UI suitable for tablet devices with touch, lower power consumption, a new application model, new asynchronous APIs, and tighter security.
The core of Windows API improvements was a new multiplatform component system, WinRT, which is a logical development of COM. With WinRT, a programmer can use native C++ code, C# and .NET, and even JavaScript and HTML to develop applications. Another change is the introduction of a centralized application store, which did not exist on the Windows platform before.
Being a new application platform, Windows 8 had backward compatibility and allowed us to run the usual Windows applications. This lead to a situation where there were two major classes of applications: the Windows Store applications, where new programs are distributed via...