There are three modes of XAML bindings exists for either Binding and x:Bind:

• OneTime: Update happens only once, on initialization of the view during InitializeComponent() call. (ViewModel[sends data when initializing] -> View)
• OneWay: View is updated when ViewModel changes. But not in the reverse direction. (ViewModel -> View)
• TwoWay: View is updated when ViewModel changes and vice versa. (ViewModel <-> View)

Default mode of Binding is OneWay and that of x:Bind is OneTime.

Select the modes like this:

<TextBlock Text="{Binding SomeText, Mode=TwoWay}" /> <!-- Binding -->
<TextBlock Text="{x:Bind SomeText, Mode=OneWay}" /> <!-- x:Bind -->

• When calling methods directly from the view.
• If performance matters really bad (scientific spaceship stuff)
• When you want to get compile time errors

• Use it if you want to be flexible about the source type of your data. It won't bind to an actual property but to its name.
• If you want to bind to the DataContext