Movie clips are versatile sorts of symbols. Part of their power is that they can contain animations and other symbol instances. Whenever you need to have a repeating action in your animation, you can use a movie to contain the repetitious element. This way, you only need to animate it once instead of multiple times. More advanced examples of this technique are used in walk cycles.
In this recipe, you will create a movie clip symbol that has an animation inside it. Then, you will place multiple instances of this symbol on your stage. For an example of movie clips in action, take a look at the movieclip.fla file in the Chapter 9 folder. The demo file shows both a beginner-level use of a movie clip to create animated bubbles, as well as an advanced use of a movie clip to animate the balloon man swimming.