DMX
DMX stands for Digital Multi-PleXing, and it refers to the DMX512 spec, which means 512 channels in a universe. There isn’t a lower number of channels in a universe, as far as I know, so you can use the terms DMX and DMX512 interchangeably. If you are a stickler, there is a more recent spec (circa 1998) known as DMX512A, which is backward compatible with DMX512, but unless you are building the actual DMX circuit boards, it shouldn’t impact you.
The Beginning
It is 1986, and remote lighting control is a clunky mess reserved for live theater