A function key is a key on a computer or terminal keyboard which can be programmed so as to cause an operating system command interpreter or application program to perform certain actions, a form of soft key. On some keyboards/computers, function keys may have default actions, accessible on power-on.
Surge definition, a strong, wavelike, forward movement, rush, or sweep: the onward surge of an angry mob. See more.
A surge arrester is device that intercepts electrical surges and sends the spike to ground before it can hurt a connected device. These arresters are also known as surge protectors or lightning arresters, but there are some very small differences between these devices. In most cases, when a surge arrester intercepts a power surge, it fuses itself to prevent transmission. This will stop the surge, but it also destroys the device.