They also make MIDI guitars, basses, violins, trumpets, saxes, even cymbals. You plug them into your synth or drum machine (which is really a synth) and program whatever voice you want to use. The beauty of that is several fold: first - these are MIDI tracks and so can be manipulated the same way MIDI can. Second - you can program any voice into these MIDI instruments and play them with that instrument's characteristics. You can take a timpani voice, put it in a MIDI violin and play the timpani as though it was a violin. That's a fantastic expansion of the musical vocabulary. Say you have a MIDI violin but what a bowed bass violin sound--just program the violin with a bass violin sound and saw away. No one can tell the difference. You can even play an extremely fast violin run up the neck and it will sound like the bass is doing it.

Because the tracks are MIDI, you can also change their voices after they were already recorded. Didn't like that trumpet voice you used when you played the MIDI trumpet? Just remove it and assign a new one. No re-recording necessary. What to change the key without altering the tonal characteristics? Just tell the computer to change it to whatever key you want. Want to change just one note in the solo? Bring up that track, locate that note on the graph and change it--any parameter you want such as pitch, tone, duration, volume, etc. or any combination of those. No re-recording necessary. You can speed up the tracks or slow them down and they don't lose their tonal quality. You can bounce tracks all over the place and never lose a bit of sound quality which is impossible with analog tape. You can bounce a track a million times and it still sounds identical to the original track. Can't beat that.

Korg is very good. So is Yamaha.