Napster's music catalog has expanded to over 11 million songs, 6 million of which are DRM-free. Songs come in WMA or MP3 format. WMA files are compatible with almost all music players except iPods, while Napster's library… of MP3s can be played on all music players. While you can buy songs individually, Napster is unique in that it offers a monthly subscription service, which allows you to listen to any song or album in the Napster catalog as long as you keep your subscription current. There is also a Napster app for the iPhone/iPod touch.