Fn key
Provided by the ASK Keyboard Dictionary
Aka/also known as: Fn, function layer key, function key
The Fn key is a modifier key commonly found on laptops and potentially other small form-factor keyboards used to access standard keys unable to be physically placed on small keyboards, or extra system/media keys (volume, brightness, microphone, etc. control) or OEM-specific keys (like a laptop's help portal) not found on standard keyboard layouts. Unlike common modifier keys like Ctrl and Alt, Fn typically only exists on the keyboard's controller electronics and the host computer doesn't see when it's pressed as it does. As such for laptops, it's usually impossible to remap the Fn key, though some BIOS/UEFI firmware and OEM-specific software might allow limited customisation on what it does such as a ThinkPad's Fn and Ctrl Key swap option.
