WPF , previously known as ‘Avalon’ was first released along with .NET framework 3.0 for rendering user interfaces. It uses DirectX which enabled a much better user experience than older GDI systems. WPF applications are developed with the help of XAML, an XML based markup language. XAML stands for eXtensible Application Markup Language. It defines the UI elements and their alignment and can also work with a C# backend.