You can change the kind of files that iTunes creates when you rip CDs and add them to your music library. Every file type has its own strengths and weaknesses – some have higher-quality sound, create smaller files (learn more about how to decide what file type to use).
ITunes defaults to using AAC, encoded at 128 Kbps (the higher the Kbps – kilobits per second – figure, the better the sound quality). You might want to encode at a higher rate or change to MP3. To change these settings, do the following:

