If you are new to the Windows platform, or coming from the worlds of .NET, Windows Forms or Silverlight, you might be wondering with a UWP app actually is.
As a famous book once said, "Don't panic!" Everything will soon become clear.
A Universal Windows Platform (UWP) app is a Windows experience that is built upon the Universal Windows Platform (UWP), which was first introduced in Windows 8 as the Windows Runtime. At the core of UWP apps is the idea that users want their experiences to be mobile across ALL their devices, and they want to use whatever device is most convenient or productive for the task at hand.