|  | Compression settings and hard disk space

When you add a song to the library, a compressed version of the song is stored on your hard disk. The amount of space the file takes up depends on the song and the import settings in iTunes. The settings also affect the audio quality of the imported song. Larger files take up more hard disk space, but sound better. If you're transferring files to a portable MP3 player, set the import preferences to Good setting so you can fit more songs on the player. As a rule of thumb, the Good setting creates files that are 1 MB in size for each minute of music.
The WAV and AIFF encoders do not compress the songs. They make files that are several times larger than MP3 files and take up a large amount of hard disk space.