XAML (pronounced zammel) is an acronym for eXtensible Application Markup Language and is an XML-based specification for defining UI Although XAML was created specifically for WPF. This is technically called a declarative programming model. WPF will take that definition and convert it into real elements on the screen.
XAML documents are strict XML. Every tag (for example, StackPanel or Label) and attribute (for example, Margin or FontSize) must correspond to a valid .NET type or property. If a tag has the wrong case or an unknown attribute is used, the resulting XAML won’t work.