DMX512 has run lighting rigs since 1986: a serial stream of up to 512 channel values, repeated many times per second, each fixture reading the channels at its address. A moving head might consume sixteen channels for pan, tilt, color, and gobos.
Modern rigs carry the same universes over the network as Art-Net or sACN, multiplying capacity and letting software speak to lights without dedicated hardware chains.
For audiovisual shows DMX is the bridge between the visual world and the physical room: the same analysis driving pixels can drive fixtures, and tools on both sides translate between DMX, MIDI, and OSC.