title: New to XAML. What does the x: and :x mean?
body: <p>I'm new to XAML. And I wonder what all the x: and :x are all about. Tutorials about XAML does not explain this (or I haven't read enough yet).</p>
  
  <p>For example:</p>
  
  <pre><code>&lt;Window x:Class="WpfTutorialSamples.WPF_Application.ResourceSample"
          xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
          xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
          xmlns:sys="clr-namespace:System;assembly=mscorlib"
          Title="ResourceSample" Height="150" Width="350"&gt;
      &lt;Window.Resources&gt;
          &lt;sys:String x:Key="strHelloWorld"&gt;Hello, world!&lt;/sys:String&gt;
      &lt;/Window.Resources&gt;
      &lt;StackPanel Margin="10"&gt;
          &lt;TextBlock Text="{StaticResource strHelloWorld}" FontSize="56" /&gt;
          &lt;TextBlock&gt;Just another "&lt;TextBlock Text="{StaticResource strHelloWorld}" /&gt;" example, but with resources!&lt;/TextBlock&gt;
      &lt;/StackPanel&gt;
  &lt;/Window&gt;
  </code></pre>
  
  <p>What does x mean in these lines?</p>
  
  <ul>
  <li>Window <strong>x</strong>:Class="WpfTutorialSamples.WPF_Application.ResourceSample"</li>
  <li>xmlns:<strong>x</strong>="http://schemas.microsoft.com/winfx/2006/xaml" sys:String</li>
  <li><strong>x</strong>:Key="strHelloWorld">Hello, world!
  </ul>