This article by Ruben is a nice, jargon-free explanation of the AS3 event model, which applies to other languages in concept if not in syntax. It’s worth getting a handle on this powerful tool and also to keep in mind that it is not the only way to send signals between loosely couple objects in a software project. In fact the Signals and Slots methods used in other platforms such as Qt are very useful extensions of the event model. John Lindquist has a video tutorial using the AS3-Signals library for AS3 here. There is also Senocular’s post on the technical details of using the Event Model to handle how an event moves through you application