Since we talked about display objects, it is a good idea to have a look at the ActionScript 3 display objects class hierarchy. The diagram below says it all.
DisplayObject, InteractiveObject, DisplayObjectContainer cannot be instantiated. Static Text and MorphShape can only be created at authoring time. The most interesting for us are the classes Sprite, Shape, and MovieClip. Sprites and MovieClips inherit from InteractiveObject and from DisplayObjectContainer. Thus, they can have children and can respond to events. Shapes cannot do either but, as we saw in our Solar System example, we can draw in them, position, scale and rotate them.