I see a lot statements like

<TextBox x:Name="txtInput" />

or like 

<BooleanToVisibilityConverter x:Key="boolToVis" />

Why the x: is needed and what it gives me.

<DockPanel.Resources>
  <c:MyData x:Key="myDataSource"/>
</DockPanel.Resources>

And here we have also the c:

Thanks for help

wpf xaml
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