Touch Wheel

The Touch Wheel was a means of providing input to the 2nd and  3rd-generation iPods.

History
The first iPod, released in October 2001, featured a physically-moving Scroll Wheel, with a center selection button in the middle of the wheel and four push-buttons around the wheel for menu, previous track, next track, and play/pause. The 2nd-generation iPod, released in July 2002, featured the Touch Wheel, which replaced the physically-moving wheel with a touch-sensitive version surrounded by the four push-buttons. The 3rd-generation iPod, released in April 2003, moved the four outside push-buttons to the top, and replaced them with LED-lit touch-sensitive buttons.

Replacement
The iPod mini and the 4th-generation iPod, both released in 2004, made the four buttons into clicking push buttons, and embedded them below the four directional edges of the wheel. This became known as the Click Wheel, which was also adopted by the first five generations of the iPod nano.