What is a MIDI guitar?
A MIDI guitar is any guitar — or guitar-shaped controller — that reports each note as MIDI data: pitch, velocity and timing, with no audio signal involved. That data can drive a synth, a sampler or a browser instrument, which is why a guitarist can write a piano arrangement without touching a keyboard. What is unique about a MIDI guitar is polyphony: unlike a MIDI keyboard, six strings sound independently, so a MIDI guitar controller has to track six pitches at once.