Cellular Automaton

A cellular automaton is a grid of cells, each in one of a finite set of states, updated in discrete steps by a rule that depends only on a cell's own state and its neighbours'. All cells update simultaneously.

Conway's Game of Life is the famous instance: cells live or die by neighbour count, and the result generates gliders, oscillators, and structures capable of universal computation. The point it demonstrates — that extremely simple local rules produce unbounded global complexity — is the reason automata matter beyond recreation.

They are practically useful for cave and terrain generation, fluid and fire approximation, crowd flow, and ecological simulation. A multi-species variant with predation, reproduction, and decay produces an evolutionary arms race whose visual behaviour is genuinely unpredictable, which is exactly what makes it good generative art.

Two implementation notes. Simultaneity is load-bearing: updating in place lets a cell see its neighbour's new state, which produces a different and usually wrong system. Double-buffering is the fix. And boundary handling is a design decision — wrapping the grid into a torus, treating edges as permanently dead, or clamping each produce visibly different behaviour at the margins.