XAML means Extensible Markup Language is a language to write user interfaces in Windows Presentation Foundation applications. XAML simplifies the creating user interfaces with windows presentation foundation and .net framework 3.0. We can create visible user interface controls and component via XAML.
I have found a great article that articles describes whole aspects of XAML with starting from what is XAML? to next level of programming in .net framework 3.0 and windows presentation foundation.
here is the link for that:
http://msdn2.microsoft.com/en-us/library/ms752059.aspx