If you're not sure which format you need, then it's probably MP3! MIDI needs greater technical knowledge, but gives greater possibilities. MIDI arrangements can be played on:
Unlike audio recordings, no actual sound is recorded! A MIDI file contains note information, “play middle C” and it specifies one of 128 instruments to play it on. The quality of the instrument sounds depends on the quality of your keyboard, MIDI File Player, or computer software/soundcard.
Some devices and Apps allow you to transpose the pitch, change instruments, or mute tracks to be combine the track with live musicians. More sophisticated software or hardware allows you to edit the MIDI files to personalise the arrangements even more. You can change tempos, remix levels. Copying and pasting to repeat sections is possible with a bit of know how.
General MIDI & XG
The General MIDI (GM) 128 instrument set became a standard. Yamaha developed an advanced version called XG with a wider variety of: (1) instrument sounds (2) drum kits (3) effects - giving superior electric guitar sounds.
WorshipTrax MIDI Files are supplied in both General MIDI and Yamaha XG format to ensure both full compatibility with all GM devices, and to take full advantage of XG features if you have a Yamaha XG device.