XAML is the acronym for Extensible Application Markup Language. It’s a markup language based on XML, and its purpose and philosophy are very similar to HTML. Every control that can be placed on a page, whether a button, text box, or custom controls, is identified by a specific XML tag. Like XML, the structure is hierarchical; you can place tags inside other tags. For example, this hierarchical structure is how you can define the layout of a page, thanks to some controls that act as a container for other controls, like Grid or StackPanel.
The following is a sample of the XAML that defines a Windows Phone page:
<phone:PhoneApplicationPage x:Class="FirstApp.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:phone="clrnamespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
xmlns:shell="clrnamespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d"
FontFamily="{StaticResource PhoneFontFamilyNormal}" FontSize="{StaticResource
PhoneFontSizeNormal}" Foreground="{StaticResource PhoneForegroundBrush}" SupportedOrientations="Portrait" Orientation="Portrait" shell:SystemTray.IsVisible="True">
<Grid x:Name="LayoutRoot" Background="Transparent">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
<StackPanel>
<TextBlock Text="This is a page" />
</StackPanel>
</Grid>
</Grid>
</phone:PhoneApplicationPage>