iPod is a brand of portable media players designed and marketed by Apple and launched in October 2001. Devices in the iPod range are primarily digital audio players, designed around a central click wheel — with the exception of the iPod shuffle, which uses buttons because of its small size. As of September 2006, the line-up consists of the video-capable fifth generation iPod, the smaller second generation iPod nano, and the display-less second generation iPod shuffle. The iPod line used to contain the iPod mini, until being discontinued for the introduction of the iPod nano. The full-sized model stores media on an internal hard drive, while the iPod nano and iPod shuffle use flash memory due to their smaller size. Like many digital music players, iPods can also serve as external data storage devices.

Apple's iTunes software is used to transfer music to the devices. As a free jukebox application, iTunes stores an entire music library on the user's computer and can play, burn, and rip music from a CD. It can also transfer photos, videos, games, and calendars to the 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 April 2007, the iPod had sold over 100 million units worldwide, making it the best-selling digital audio player series in history.