XAML

Extensible Application Markup Language (XAML, pronounced zammel [zæml]) is a declarative XML-based language created by Microsoft which is used to initialize structured values and objects. It is available under Microsoft's Open Specification Promise. The acronym originally stood for Extensible Avalon Markup Language - Avalon being the code-name for Windows Presentation Foundation (WPF)
XAML is used extensively in .NET Framework 3.0 technologies, particularly Windows Presentation Foundation (WPF) and Windows Workflow Foundation (WF). In WPF, XAML is used as a user interface markup language to define UI elements, data binding, eventing, and other features. In WF, workflows can be defined using XAML.
XAML elements map directly to Common Language Runtime object instances, while XAML attributes map to Common Language Runtime properties and events on those objects. XAML files can be created and edited with visual design tools such as Microsoft Expression Blend, Microsoft Visual Studio, and the hostable Windows Workflow Foundation visual designer. They can also be created and edited with a standard text editor, a code editor such as XAMLPad, or a graphical editor such as Vectropy.
Anything that is created or implemented in XAML can be expressed using a more traditional .NET language, such as C# or Visual Basic.NET. However, a key aspect of the technology is the reduced complexity needed for tools to process XAML, because it is based on XML. As a result, a variety of products are emerging, particularly in the WPF space, which create XAML-based applications. As XAML is simply based on XML, developers and designers are able to share and edit content freely amongst themselves without requiring compilation. As it is strongly linked to the .NET Framework 3.0 technologies, the only fully compliant implementation as of today is Microsoft's