This course introduces Extensible Application Markup Language, or XAML (pronounced zammel), as a declarative, XML-based markup language that allows you to define an application's user interface (UI) at design time. Creation of rich user interfaces in XAML is simplified because the design and code elements of the application are separated. XAML-based applications are supported by both Microsoft Visual Studio 2010 and Microsoft Expression Blend 4. XAML is a core feature in the creation of applications based on both Windows Presentation Foundation (WPF) and Microsoft Silverlight®. An understanding of the benefits of, development tools for, and structure of XAML-based applications should provide you with a solid foundation for creating XAML-based applications.