The iPod was not the first digital music player (that distinction goes to the MPMan, which hit South Korean stores in March of 1998), but after its introduction in October of 2001, it quickly dominated the market. The first generation iPod offered only 5 to 10 GBs of storage, with a mechanical scroll wheel on its face that formed a ring around the main select button. An additional ring surrounding the scroll wheel was outfitted with four more control buttons. The second-generation iPod, released in July of the following year, gave the scroll wheel touch-sensitive technology and doubled the device’s storage capacity, but left most other features the same.

The third-generation iPod, introduced in April of 2003, represented a major change from the previous design. In addition to increasing the device’s potential storage to 40 GB, the buttons that had surrounded the scroll wheel were moved up to form a row just below the screen. The device was also slimmer, but the battery life dropped from 10 hours to a measly eight. The fourth-generation iPod, July 2004, moved the buttons yet again, this time underneath the surface of the scroll wheel itself, a trick Apple first used on the iPod Mini in January 2004.