Particle systems are primarily responsible for creating special effects and animation where many parts or things must move together as something cohesive, such as rain, snow, sparkles, fairy dust, flocks of birds, swarms of bees, and more. They're also used to simulate intangible things, such as light rays, dust, ghosts, holograms, and others.

A fire particle system in action

Unity 5 ships with a wide range of premade particle systems that can simply be dragged and dropped into a scene to create the most common particle effects, such as explosions, fire, steam, and smoke. To access these effects, import the Particle Systems asset package into your project by going to Assets | Import Package | ParticleSystems from the application menu. After this import, all the premade systems will be available by going to Assets | ParticleSystems | Prefabs from the Unity Project panel.

Unity 5 ships with many premade particle systems

Despite the differences between them, all particle systems...