Overlay keyboard

An overlay keyboard is a specialized keyboard with no pre-set keys. Each key can be programmed with a wide range of different functions. Overlay keyboards are often used as a quick and easy way to input items with just two buttons.

Overlay keyboards generally consist of a flat grid of unmarked buttons. After the keyboard is programmed, a sheet, called an overlay, is placed overtop to identify each key. The overlay can consist of any combination of words, symbols, or even pictures.