Extensible Application Markup Language (XAML, pronounced zammel ([zæ:mɛl])) by Microsoft is a declarative XML-based language used to initialize structured values and objects.
XAML is used extensively in the .NET Framework 3.0 technologies, particularly in Windows Presentation Foundation (WPF), where it is used as a user interface markup language to define UI elements, data binding, eventing, and other features, and in Windows Workflow Foundation (WF), in which workflows themselves can be defined using XAML. The serialization format for workflows was previously called XOML,
to differentiate it from UI markup use of XAML, but now they are no
longer distinguished. However, the file extension for files containing
the workflow markup is still "XOML".
XAML elements can map directly to Common Language Runtime (CLR) object instances whereas attributes can map to CLR
properties and events on those objects. In typical usage, XAML files
will be produced by visual design and developer tools, such as Microsoft Expression Blend, Microsoft Visual Studio, XAMLPad or the hostable Windows Workflow Foundation (WF) visual designer.
XAML files are sometimes compiled into a .baml binary files, which may be inserted as a resource into a .NET Framework
assembly. At run-time, the framework engine extracts the .baml file
from assembly resources, parses it, and creates a corresponding WPF
visual tree or workflow.
(Source: http://en.wikipedia.org/wiki/Extensible_Application_Markup_Language)
