What is the Genius feature?
The iTune Genius feature creates playlists based on a selected track, generated from music stored in your iTunes library. Genius learns your preferences and how you relate songs by following your listening patterns. It then uses those patterns along with other track information such as artist, genre, etc., to create its playlist. The more you use iTunes, the more accurately Genius can anticipate your preferences. When you update Genius to the iTunes store, that information is added anonymously to that of everyone else who updated to the iTunes database. This accumulated data allows the Genius feature to make increasingly intelligent recommendations. This feature is available in the current versions of the iPod nano, iPod touch, iPod classic, and iPhone. In this case, Genius generates its playlist for the selected song from music stored on the player.