The core mechanism for displaying Silverlight pages is the
UserControl class. The UserControl element appears at the top of every user
control. This root element is a prime choice for storing static resources
(discussed briefly later), as well as any namespaces (Silverlight uses
namespaces to point to namespaces in an assembly).
The UserControl class is a content control, which means that
it has only one property for storing children: Content. This means only one
root level element can appear underneath the UserControl class, excluding
complex properties (like UserControl.Resources, where Resources is a collection-based
Fortunately, other controls can contain a collection of
children, so the user control can host a single control, which that single
control can then host multiple controls. We'll get into the specifics of this
soon. The first control that appears at the top of the user control by default
is discussed in the next section.