Particle system
A way to draw fuzzy, shapeless phenomena — fire, smoke, rain, sparks, magic — as clouds of thousands of tiny, short-lived points or sprites.
William Reeves coined the term at Lucasfilm for the "Genesis effect" in Star Trek II: The Wrath of Khan (1982) and described it in a classic 1983 SIGGRAPH paper. Each particle carries a position, velocity, colour, size and lifespan. An emitter spawns new ones, a simulation step moves and ages them, and the renderer draws them — usually as sprites turned to face the camera, with additive blending for glow.
Because the particles are many and identical in shape, they are a textbook case for GPU instancing: the whole cloud ships in a handful of calls. Modern engines go further and run the entire simulation on the GPU via compute shaders, so millions of particles never cross the CPU or weigh on the draw call budget.