what is XAML in windows presentation foundation?

Hi.Briefly:

XAML (pronounced as Zammel) is a declarative XML-based language by which you can define objects and properties in XML. A XAML document is loaded by a XAML parser. The XAML parser
instantiates objects and sets their properties. XAML describes objects, properties, and the relations between them. Using XAML, you can create any kind of objects, graphical or non-graphical. WPF parses the XAML document and instantiates the objects and creates the relations defined by the XAML. So XAML is an XML document which defines objects and properties and WPF loads this document in actual memory. For example:

<Grid>
        <ListView x:Name="myListView" Background="Gray" FlowDirection="RightToLeft" Loaded="myListView_Loaded">
            <ListView.View>
                <GridView AllowsColumnReorder="True" >
                    <GridView.Columns>
                        <GridViewColumn Header="ProductName" Width="150" DisplayMemberBinding="{Binding ProductName}"/>
                        <GridViewColumn Header="Unit Price" Width="100" DisplayMemberBinding="{Binding UnitPrice}"/>
                    </GridView.Columns>
                </GridView>
            </ListView.View>
        </ListView>
    </Grid>

I hope this help you.
Good Luck