Midi vs. Sound
Think of MIDI like the old time player pianos where you put a roll into it and the punches on the paper roll told the piano what notes to play. MIDI is a way for computers and musical instruments to communicate what is being played. When you plug your keyboard into your computer and enable it in Cakewalk, then Cakewalk records what notes you are playing on your keyboard (makes a piano roll file). Then when you tell Cakewalk to play this file back it communicates to your keyboard and says play these notes just like a person was sitting there playing these notes. The distinction here is you are recording and playing back your performance (which keys you pressed, how hard you struck the keys, how long you held the keys for sustain, etc...). No sound is actually being recorded, just the PERFORMANCE. When you play it back, the keyboard regenerates the sounds on the fly just as if you were actually sitting there performing the music again. Same thing applies to other MIDI enabled instruments (drums, guitar, saxaphone, etc...). This opens up all kinds of possibilities, you can redirect the recorded MIDI file to a completely different sound or instrument. Example... you record MIDI of you playing piano song, then you have Cakewalk play this MIDI back to your keyboard but you change the sound on your keyboard to guitar, it will play the same song, but now you will hear guitar instead of piano. Get it?