If you’ve ever used audio software on the computer, you probably know that MIDI exists: a signalling protocol that allows controllers to control virtual instruments like synths. It’s also the protocol used by real audio hardware to talk to each, and you can think of it as the language in which, rathar than communicating a fluctuating voltage signal or series of discrete sample values, devices talk about what is being done on them (“A4 got pressed”, “F4 got released”, “the mod wheel moved down”, etc).
