When you buy songs and albums from the iTunes Store, the files you download are in the Advanced Audio Coding (AAC) format. However, Apple has another codec, Apple Lossless Audio Codec (ALAC), that you can use when ripping CDs or converting other file types. This article explains the difference between the two formats.

The ALAC format option in iTunes is short for Apple Lossless Audio Codec (or just Apple Lossless), and it doesn’t compress your music to the point where the sound quality is affected. The audio is still compressed like AAC, but the big difference is that the sound quality remains identical to the source. This lossless audio format is similar to other formats you may have heard of, such as Free Lossless Audio Codec (FLAC).

The file extension used for ALAC is .m4a, which is the same as the standard AAC format. This can be confusing if you see a list of songs on your computer's hard drive, all with the same .m4a file extension. Because of this, you won't visually know which songs are encoded with ALAC or AAC unless you enable the Kind column option in iTunes. To enable the Kind column, select View Options > Show Columns > Kind.

The main reason to use the ALAC format is if audio quality is important to you. However, here are a few more advantages of ALAC: