Irene
I think a bit more depth about midi might be useful - what it is, why we use it and why it is one of the most powerful tools in music.
MIDI means Musical Instrument Digital Interface, and is a protocol to allow transfer of musical data between hardware like some musical instruments, computers and other peripherals. It contains no sound, just the ‘instructions’ to a device which allows it to play music when the device has the right sound processors and effects. In some ways you can think of it as doing digitally what you do when you play and operate the keyboard.
MIDI has many advantages in editing, and music transfer, not the least of which is that the files are relatively small, - much, much smaller than even the very compressed audio files like MP3s. So speed of transfer and use of memory space is optimal. In fact, in the fairly recent past, when memory and disc drive was expensive, many of these keyboards could only record using midi. You will have seen the advantage of this in the way that you can download large amounts of these files, often zipped, fairly efficiently.
Advances in the technology and cost reduction, now allow audio recording as a matter of course on most of the best keyboards. But there are still advantages in recording to midi first, and doing any editing before changing it to an audio file. Most of our most experienced players will probably still do this before finalizing a mix, or edit, and finally changing to a finished audio file - like .wav or MP3.
Style files are another example of the use of midi. Style files are essentially midi loops which the keyboard software can manipulate to allow you to drive accompaniment by pressing keys. In fact you could say that MIDI was the enabler of sophisticated, yet low cost, arranger keyboards becoming popular.
A couple of simple examples of where midi makes editing easier - seamless elimination or replacement of sections, something much harder to do when there is sound wave files. Another is that the tempo of a midi can be changed without changing pitch, something which takes very sophisticated software when sound waves are involved. Try playing an old fashioned record at the wrong speed and you will know what I mean. This only scratches the surface of why midi is an immensely important tool in music.
Of course, all this may not directly answer your original question as to how you personally might use it. First thing is not to get confused by the ‘song’ word because ‘song’ is often used interchangeably for both audio and midi recordings.
Audio recordings are pretty fixed in nature, but a midi recording allows more manipulation by you. For example you can play it at any speed and the key or pitch doesn’t change. That might be good for practice, or simply because you prefer a different tempo. You could also edit it quite extensively if so desired.
Sorry for the long read, but hope you find this useful, - or at least informative.
Mike
