An instrument is a sound-synthesis algorithm with certain parameter
settings, usually designed to emulate a specific real-world
musical instrument or to achieve a specific sort of sound effect.
Instruments are typically stored in collections called soundbanks.
Before the instrument can be used to play notes, it must first be loaded
onto a synthesizer, and then it must be selected for use on
one or more channels, via a program-change command. MIDI notes
that are subsequently received on those channels will be played using
the sound of the selected instrument.