An iPod is a portable device for storing and playing audio files encoded by MP3 or AAC compression algorithms. Designed by Apple Computer, iPods have distinctive styling and can hold anywhere from a few hundred to ten thousand songs.

Released in 2001, the original iPod came with a body of white Lucite and chrome. Two years later Apple released the iPod Mini, approximately one-third the size of the original iPod and encased in a variety of shiny metallic colors. The smallest member of the iPod family, the Shuffle, reduced the size down to that of a package of stick gum and looked very much like the original. All iPods came with distinctive white headphones.

The larger iPod and the iPod Mini use an extremely small hard disk for storage. The Shuffle uses a type of memory known as flash; unlike the memory found in computers, flash memory does not lose its contents when the power is turned off. As the prices and capacities of both hard disks and flash memory continue to fall, the storage capacity of all three models has increased over time.

Apple's iPod continued the company's tradition of creating technology that is easy to use. When connected to a personal computer (PC), Windows or Macintosh, the iPod communicates with a piece of Apple software called iTunes. The iPod and iTunes work together to synchronize the songs available on the iPod to those available on the PC. This happens automatically, without any intervention being required from the user. This ease of use was a primary reason for the iPod's domination of the portable MP3 player market.

In addition to playing MP3 audio files, the iPod plays AAC. AAC, or Advanced Audio Coding, was developed by Dolby Labs as part of the MPEG-4 audio/video standard. While technically advanced as a compression algorithm, AAC's principle difference from MP3 is its ability to support Digital Rights Management (DRM). DRM is a response to the type of song sharing first enabled by websites like Napster. By encoding legally purchased songs with digital signatures, it increases the difficulty of sharing them inappropriately.