XAML

(eXtensible Application Markup Language) An XML-based set of tags used to describe objects and events when programming .NET-based Windows applications. Pronounced "zammel," XAML was introduced with .NET Framework 3.0. XAML is used to define elements in the user interface (Windows Presentation Foundation) and in workflow structures (Windows Workflow Foundation).

The "A" in XAML originally stood for "Avalon," the former name of Windows Presentation Foundation. See .NET Framework, Silverlight, XML Paper Specification and WPF.