Provide some instances where you have "xmlns:x" namespace in XAML ?

Answer

There are two common scenarios where we use “xmlns:x” namespace :-

To define behind code for the XAML file using “x:class” attribute.

<Page
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  x:Class="MyNamespace.MyCanvasCodeInline"
>

Second to provide name to an element.

<StackPanel x:Name="myStack" />