How does MIDI work?

MIDI, or Musical Instrument Digital Interface, was introduced to the technological industry in 1983. It is defined as an industry-standard protocol that allows electronic musical instruments, computers and other electronic equipment to communicate, control and synchronize with each other. It was designed by Dave Smith of Sequential Circuits, Inc to allow the keyboard of one synthesizer to play notes generated by another.

MIDI enables computers, synthesizers, MIDI controllers, sound cards, samplers and drum machines to control one another and exchange system data. Since MIDI does not send sound waves, like a tape recorder, to communicate, it uses digital data sent in the form of multiple "on" and "off" signals through a MIDI cable instead. As a result, MIDI files take up less space than digital audio files.

The use of MIDI devices is quite popular with most music recordings today. Most MIDI devices have both MIDI input and MIDI output connectors. These connectors are part of the MIDI Interface. MIDI Interface moves internal binary data to the MIDI Out connector for transmission to another device's MIDI In connector, all in pure MIDI message form. Some instruments have a third MIDI jack labeled MIDI 'Thru' that acts as an unprocessed MIDI Out Connector.

A MIDI message is a series of extensive 'musical commands' that electronic instruments use to control each other. These MIDI commands consist of 2-3 data bytes that are actually sets and series of numbers. Each MIDI message compares to a specific musical action.