What does x: stand for in x:key and x:name ? Why the colon and why not y:?
This is confusing to me. Why do we have to use x:Key= and x:Name= in place of key= and name=?
Where does this x come from?
The 'X' is an alias for an imported namespace (See the declaration of your XAML).
so when you type x, you use resources from that defined namespace. Actually, Name and Key are defined in the xaml namespace.