The events that cause new particles to be spawned.
| Birth | Spawns new particles when particles from the parent system are born. | 
| Collision | Spawns new particles when particles from the parent system collide with something. | 
| Death | Spawns new particles when particles from the parent system die. | 
| Trigger | Spawns new particles when particles from the parent system pass conditions in the Trigger Module. | 
| Manual | Spawns new particles when triggered from script using ParticleSystem.TriggerSubEmitter. |