About MIDI files
A MIDI file can be loaded in Synthesia or similar software so you can play the song directly on your computer, tablet or phone. They can also be used for many other purposes. Check out What are MIDI files and how to use them? for more info.
Do you want to test a demo MIDI file before you make a purchase? MIDI files can be used on many systems in many different ways. Download this demo MIDI file to be sure it works for your purpose.