apple itunes will be selling top music without DRM. But that doesn't mean the files will be MP3. Apple is using AAC (Advanced Audio Coding). AAC uses newer technology that provides similar quality to MP3 but in a smaller, more compressed file. AAC comes in both protected (Apple's FairPlay DRM) and open versions.

Because AAC is open it could be licensed and used by any software or hardware player. However unlike MP3 it is not widely supported. Microsoft Zune plays AAC files, while Creative and SanDisk don't or do only in one model.

EMI is allowing online music stores a choice of formats for open files. While Apple went with AAC, sites can also use WMA and MP3 formats. AAC was developed by Dolby, Fraunhofer, AT&T, Sony and Nokia