A particle system manages a population: each particle has position, velocity, age, and a short life spent obeying forces. Simple per-particle rules compound into organic mass behavior, which is why the technique renders everything from campfire sparks to starling murmurations.
William Reeves named and formalized the idea for the Genesis effect in Star Trek II (1982); GPUs made millions of particles a live-performance budget.
For audio work, particles map naturally to events: a transient spawns a burst, sustained energy feeds emission rate, and the swarm’s motion carries the groove. Photism’s drift scene is a particle system riding a flow field, with hits launching new comets.