What is a Function Key?

G. Wiesen

A function key is a key on a keyboard, usually for some kind of computer, that runs or executes various programs or aspects of a program when pressed. These keys act in ways other than standard single function input keys, such as letters and numbers that generally indicate a letter or number to be entered into a system regardless of the program being used. The exact purpose of these keys is typically indicated by the program a user is currently interacting with, though certain functions are somewhat standard in various programs. A function key is typically designated with an “F” or “Fn” on the key and often a number as well, for ease of identification.

A computer and keyboard with a function key.
A computer and keyboard with a function key.

Also called “F-keys,” a function key operates by allowing a computer program to indicate what operations will be run when the key is pressed. While “hot keys” can be established for most computer programs, a function key tends to be universally acknowledged as being separate from the other keys on a keyboard and used for various other purposes. These functions can be established within a program itself, or a program can allow a user to alter the function of these keys to do different things.

A woman pressing a function key.
A woman pressing a function key.

Though different programs establish different purposes for various function keys, there are some common uses that can be applied to different programs. Many web browsers, for example, allow F5 to be pressed to refresh a web page. F3 can typically open a search box, and many different programs use F1 as a function key to open a help menu or window while using the program. Most versions of Microsoft® Windows® allow a user to close a currently selected window by pressing Alt+F4, and if F8 is pressed while Windows® is starting, it will start in safe mode.

Other Microsoft® products also use function keys quite prodigiously for a number of different features. In Microsoft® Word®, for example, F7 runs a spell check on the currently opened document, and in PowerPoint® F5 will start a slide show. The Mac OS® operating system utilized in Apple® computers often give a function key control over one of numerous options, such as changes to speaker volume and monitor brightness.

Function keys are also commonly used in basic input/output systems (BIOS) while starting a computer to allow for a number of features. F10 while in a BIOS program will typically save and exit the program, restarting the computer in the process, while F7 can often load up the optimal BIOS configuration for a computer. Most keyboards include a number of different keys for various functions, and some keyboards feature liquid crystal display (LCD) keys that can indicate the action within a program that pressing a function key will perform.

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