This excerpt taken from the SIRI 10-K filed Mar 10, 2009.
The Apple iPod® is a portable digital music player that allows users to download and purchase music through Apples iTunes® Music Store, as well as convert music on compact disc to digital files. Apple has sold over 170 million iPods®. iPods® are compatible with certain car stereos and various home speaker systems, and certain automakers have entered into arrangements with manufacturers of portable media players that are expected to enhance this compatibility. Availability of music in the public MP3 audio standard has been growing in recent years with sound files available on the websites of online music retailers, artists and record labels and through numerous file sharing software programs. These MP3 files can be played instantly, burned to a compact disc or stored in various portable players available to consumers. Internet-based audio formats are becoming increasingly competitive as quality improves and costs are reduced.