Two Textboxes bound to each other in XAML. If the Text of the first Textbox is changed, the second one will also change.

simpleDataBindingExample.txt

<Window x:Class="BindingExample.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <TextBox x:Name="tb1" HorizontalAlignment="Left" Height="23" Margin="102,80,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="120"/>
        <TextBox x:Name="tb2" HorizontalAlignment="Left" Height="23" Margin="282,80,0,0" TextWrapping="Wrap" Text="{Binding Text, ElementName=tb1, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Top" Width="120"/>

    </Grid>
</Window>