ActionScript 2.0 is an object-oriented programming language used to add interactivity to Flash movies. It allows programming of movie clips, graphics, and buttons. ActionScript can be used to create animations and control the playback of movies through events like mouse clicks or keyboard inputs. Some key aspects of ActionScript include actions, which tell Flash what to do; variables to store data; expressions to evaluate and return values; and looping to repeat actions. Planning scripts through storyboarding goals is important before writing ActionScript code.