A MIDI instrument is known alternately as a sound module, a rackmount sampler, a rackmount synth, an external synth or an external sampler. It is simply an electronic device that can make certain kinds of noises (you could be kind and call it music Mick Jagger). Unlike a traditional musical instrument, though, it doesnt include a feature than would allow a musician to play it its kind of like a piano without keys. It is designed to be played not by a musician directly, but by another device that the musician directly controls. The reason for doing it this way is so that a musician can use one controller (such as a MIDI keyboard) to play several different MIDI instruments at once by controlling them all simultaneously when he hits a key on his MIDI keyboard, several different MIDI instruments can sound off at once if he has set it up that way in advance.
What can a MIDI instrument play? It can play whatever sounds have been built in to it typically the sounds of a variety of different traditional instruments such as a flute or a guitar, plus a wide assortment of synthesized sounds. Each type of sound is known as a patch. Modern MIDI instruments are multi-timbral,...