Why Action Script?

ActionScript is the language you use to add interactivity to Flash applications, whether your applications are simple animated SWF files or more complex rich Internet applications. You don't have to use ActionScript to use Flash, but if you want to provide basic or complex user interactivity, work with objects other than those built into Flash (such as buttons and movie clips), or otherwise turn a SWF file into a more robust user experience, you'll probably want to use ActionScript.