What is the Universal Windows Platform?

XAML (eXtensible Application Markup Language) is a special declarative language that is based on XML and is used primarily for creating interfaces.
XAML was introduced in the .NET Framework 3.0 as a part of Windows Presentation Foundation technology. Since that time developers have started using XAML in Silverlight, Windows Workflow, and Windows 8.x/Windows Phone 8.x development. Of course, we are going to use XAML in all Windows 10 applications.