MIDI, short for Musical Instrument Digital Interface, was first published in 1983 as the result of cooperation between instrument manufacturers. It carries instructions rather than sound: which note to play, how hard, when to stop, plus controller movements and program changes. Values generally run from 0 to 127, middle C is note number 60, and a single connection offers 16 channels, each of which can drive a different instrument.
MIDI 2.0, adopted in early 2020 by The MIDI Association and Japan’s AMEI, extends the original standard without replacing it. For a jazz lo-fi producer, MIDI is what turns a keyboard controller into a Rhodes, a vibraphone or a drum kit inside the DAW, and it is why programmed parts can be quantized, swung or edited note by note.