iPod® is a brand of portable media players designed and marketed by Apple and launched on October 23, 2001. The line-up currently consists of the hard drive-based iPod classic, the touchscreen iPod touch, the video-capable iPod nano, and the screenless iPod shuffle. Former products include the compact iPod mini (replaced by the iPod nano) and the spin-off iPod photo (re-integrated into the main iPod classic line). iPod classic models store media on an internal hard drive, while all other models use flash memory to enable their smaller size (the discontinued mini used a Microdrive miniature hard drive). As with many other digital music players, iPods, excluding the iPod Touch, can also serve as external data storage devices.
Apple's iTunes software is used to transfer music to the devices. As a jukebox application, iTunes stores a music library on the user's computer and can play, burn, and rip music from a CD. It also transfers photos, videos, games, and calendars to those iPod models that support them. Apple focused its development on the iPod's unique user interface and its ease of use, rather than on technical capability. As of October 2007, the iPod had sold over 141 million units worldwide (stated in "The Beat Goes On" conference) making it the best-selling digital audio player series in history.
