MIDI

Several rack-mounted synthesizers that share a single controller
Using MIDI, a single controller (often a musical keyboard, as pictured here) can play multiple electronic instruments, which increases the portability and flexibility of stage setups.

MIDI (/ˈmɪdi/; Musical Instrument Digital Interface) is a technical standard. It describes a communications protocol, digital interface, and electrical connectors. It connect a large variety of electronic musical instruments, digital devices for playing, editing, and recording music.

A MIDI recording is not an audio signal. It is more like a piano roll, identifying the pitch, start and stop time and other properties of each individual note.

The personal computer market stabilized at the same time, popularizing the MIDI format, and helped computers become a viable option for music production.

Logo of MIDI (from the MIDI Manufacturers Association)