One of the aspects of Core Animation that can be confusing is that there are degrees of it. To start with there is the animator proxy which is available to NSWindows and NSViews and allows you to animate some property transitions. Next there is the concept of layer-backed views which allow you to perform additional animation effects to your views whilst still essentially working with the familiar AppKit objects. Finally there are layer-hosting views, a scenario where you essentially use Core Animation layers to create the user interface, simply using an NSView to contain the layers. This article explains each of these in further detail and will hopefully make the distinction between them clearer.