Particle Systems are commonly used in motion graphics, visual effects and gaming environments to simulate smoke, fire, snow, explosions, dust and fog to name just a few. Particle systems are also used in abstract ways to create effects like glowing trails and magic pixie dust (think Tinker Bell). Motion has a built in particle system that's not only intuitive, but can be used to create just about anything you can imagine. Used in conjunction with Behaviors, particles can be made to obey (or break) all the laws of physics with just a few mouse clicks. Motion comes with many built in particle presets, but as you'll learn in this tutorial, Motion's interface makes it easy to develop custom particle effects.