Used carefully, sound can dramatically enhance an animation or interactive experience. Music can be used for animation soundtracks, and sound effects can add a touch of realism to an animation or a bit of life to an interface. However, it's important to remember that sound doesn't usually come without a price. Sound files can contribute significantly to the size of a SWF, and sound can be overused or used gratuitously, detracting from the overall effect. The task, therefore, is to know how and when to use sound for maximum impact.