The document discusses the architecture of the Silverlight framework. It is composed of three main layers:
1) The core presentation framework which handles UI rendering, layout, controls, media, and data binding using XAML.
2) The .NET framework which provides runtime services like memory management and a base class library. It also includes Windows Presentation Foundation for XAML parsing and Windows Communication Foundation for web services.
3) Silverlight applications consist of a web page object, presentation code in XAML, and managed code-behind files that can access the UI and implement functionality and data access.