This section provides a brief description of the architecture of WPF which spreads across both managed code and native code components. The managed code only provides the publicly exposed API. The major code portions of WPF are the PresentationFramework, PresentationCore, and milcore. The composition engine of WPF is a native component and is known as MIL (Media Integration Layer) and resides in the milcore.dll. Milcore is written in unmanaged code and the interfacing is done with DirectX at this level for providing support for 2D and 3D surfaces. WPF displays are done through the DirectX engine. The composition engine in WPF is highly performance sensitive and demands forsaking of several CLR advantages for enhancing performance.  PresentationCore (presentationcore.dll) implements the core services for WPF and the PresentationFramework (presentationframework.dll) is responsible for the presentation features of the end users. The major WPF subsystems are as follows; Object, Threading.DispatcherObject, Windows.DependancyObject, Windows.Media.Visual, Windows.UIElement, Windows.FrameworkElement, Windows.Controls.Control. Details of the WPF architecture are beyond the scope of this article.