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:

