Programmable function key
A programmable function key is a single computer keyboard key capable of being programmed to perform a specific task. For example, a key on the keyboard may be programmed to open your e-mail client. Programmable keys are found on keyboards with additional keys or buttons not commonly found on most keyboards. These specialty keyboards require extra software that enables these keys to be programmed.
The picture of the Logitech G19 gaming keyboard shows a collection of programmable function keys, labeled G1 through G12, on the left-side of the keyboard.