If you’ve bought music from the iTunes Store, you’ll have AAC files at 256 kbps (that’s kilobits per second, an indication of the quality of the compression higher numbers are better). Finally, some are uncompressed, such as WAV and AIFF they represent the exact data from a CD or a master.
Some formats are lossless, such as Apple Lossless, FLAC, and SHN these files can be converted back to their original form without the loss of a single bit.
Some are lossy, such as AAC and MP3 they save space compared to the original files, but some of the original data is lost during compression. Audio files come in a number of different formats.
