It's not something I've given much thought to, but I recently I was looking to copy some music to an SD card for the car for my Dad. I don't have the hard copies of what he wants and it's not available via more shady methods (only in .flac), and all my music is via Google Play which can't be downloaded to play via another media.
So where would one start? Does the likes of iTunes download actual .mp3 files?