Mastered for iTunes (MFiT) is a very high quality 24bit AAC (Advanced Audio Codec) audio file available from iTunes. It sounds far superior to regular MP3 files. This format is now widely used by major labels and artists who want their releases on iTunes to sound significantly better than they previously did.
Only approved mastering houses (on Apple’s MFiT providers list) can submit MFiT audio files for iTunes. Tim Turan at Turan Audio LTD is now certified, by Apple, as an approved MFiT mastering engineer.