Function key

For the modifier key that features on most compact keyboard layouts, see Fn key.

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.[1] On some keyboards/computers, function keys may have default actions, accessible on power-on.

A 104-key PC US English keyboard layout with the function keys in orange.

Function keys on a terminal may either generate short fixed sequences of characters, often beginning with the escape character (ASCII 27), or the characters they generate may be configured by sending special character sequences to the terminal. On a standard computer keyboard, the function keys may generate a fixed, single byte code, outside the normal ASCII range, which is translated into some other configurable sequence by the keyboard device driver or interpreted directly by the application program. Function keys may have (abbreviations of) default actions printed on/besides them, or they may have the more common "F-number" designations.


Flexowriter keyboard (1968) with 13 function keys on the right.
HP 9830A (1972) with 5×2 grid of 10 function keys at top left.
IBM 3277 (1972) with 3×4 grid of 12 Programmed Function (PF) keys at right.

The Singer/Friden 2201 Flexowriter Programatic, introduced in 1965, had a cluster of 13 function keys, labeled F1 to F13 to the right of the main keyboard. Although the Flexowriter could be used as a computer terminal, this electromechanical typewriter was primarily intended as a stand-alone word processing system. The interpretation of the function keys was determined by the programming of a plugboard inside the back of the machine.[2]

Soft keys date to avionics multi-function displays of military planes of the late 1960s/early 1970s, such as the Mark II avionics of the F-111D (first ordered 1967, delivered 1970–73). In computing use, they were found on the HP 9810A calculator (1971) and later models of the HP 9800 series, which featured 10 programmable keys in 5×2 block (2 rows of 5 keys) at the top left of the keyboard, with paper labels. The HP 9830A (1972) was an early desktop computer, and one of the earliest specifically computing uses. HP continued its use of function keys in the HP 2640 (1975), which used screen-labeled function keys, placing the keys close to the screen, where labels could be displayed for their function.

NEC's PC-8001, introduced in 1979, featured five function keys at the top of the keyboard, along with a numeric keypad on the right-hand side of the keyboard.[3][4]

Their modern use may have been popularized by IBM keyboards: first the IBM 3270 terminals, then the IBM PC. IBM use of function keys dates to the IBM 3270 line of terminals, specifically the IBM 3277 (1972) with 78-key typewriter keyboard or operator console keyboard version, which both featured 12 programmed function (PF) keys in a 3×4 matrix at the right of the keyboard. Later models replaced this with a numeric keypad, and moved the function keys to 24 keys at the top of the keyboard. The original IBM PC keyboard (PC/XT, 1981) had 10 function keys (F1–F10) in a 2×5 matrix at the left of the keyboard; this was replaced by 12 keys in 3 blocks of 4 at the top of the keyboard in the Model M ("Enhanced", 1984).

Schemes on various keyboards

Action on various programs and operating systems

In the classic Mac OS, the function keys could be configured by the user, with the Function Keys control panel, to start a program or run an AppleScript. macOS assigns default functionality to F9, F10, and F11 (Exposé); F12 (Dashboard); and F14/F15 (decrease/increase contrast). On newer Apple laptops, all the function keys are assigned basic actions such as volume control, brightness control, NumLock (since the laptops lack a keypad), and ejection of disks. Software functions can be used by holding down the Fn key while pressing the appropriate function key, and this scheme can be reversed by changing the macOS system preferences.

Under MS-DOS, individual programs could decide what each function key meant to them, and the command line had its own actions (e.g., F3 copied to the current command prompt words from the previous command). Following the IBM Common User Access guidelines, the F1 key gradually became universally associated with Help in most early Windows programs. To this day, Microsoft Office programs running in Windows list F1 as the key for Help in the Help menu. Internet Explorer in Windows does not list this keystroke in the help menu, but still responds with a help window. F3 is commonly used to activate a search function in applications, often cycling through results on successive presses of the key. ⇧ Shift+F3 is often used to search backwards. Some applications such as Visual Studio support Control+F3 as a means of searching for the currently highlighted text elsewhere in a document. F5 is also commonly used as a reload key in many web browsers and other applications, while F11 activates the full screen/kiosk mode on most browsers. Under the Windows environment, Alt+F4 is commonly used to quit an application; Ctrl+F4 will often close a portion of the application, such as a document or tab. F10 generally activates the menu bar, while ⇧ Shift+F10 activates a context menu. F2 is used in Windows Explorer, Visual Studio and other programs to rename files or other items.

F4 is used in some applications to make the window "fullscreen", like in 3D Pinball: Space Cadet. In Microsoft IE, it is used to view the URL list of previously viewed websites.

Other function key assignments common to all Microsoft Office applications are: F7 to check spelling, Alt+F8 to call the macros dialog, Alt+F11 to call the Visual Basic Editor and ⇧ Shift+Alt+F11 to call the Script Editor. In Microsoft Word, ⇧ Shift+F1 reveals formatting. In Microsoft PowerPoint, F5 starts the slide show, and F6 moves to the next pane.

WordPerfect for DOS is an example of a program that made heavy use of function keys.

Function Keys are also heavily used in the BIOS interface. Generally during the power-on self-test, BIOS access can be gained by hitting either a function key or the delete key. In the BIOS keys can have different purposes depending on the BIOS. However, F10 is the de facto standard for save and exit which saves all changes and restarts the system.

During Microsoft Windows startup, F8 is used to enter safe mode.

In Internet Explorer 6 and Internet Explorer 7, F12 opens Internet Explorer Developer Toolbar. F6 highlights the URL in the address bar.

Standard functions

This is a list of the standard functions assigned to each of the function keys in Microsoft Windows.[6]


  2. The completely new 2201 FLEXOWRITER automatic writing machine by Friden (advertisement), Nation's Business, Vol. 53, No. 2 (February 1965), pages 75-76.
  3. 1 2
  4. 1 2
  5. Ignite-UX Administration Guide: for HP-UX 11.00 and 11i, Appendix D (Terminal Keyboard Shortcuts), Advanced Keyboard Navigation.
  6. "What are the F1 through F12 keys?". Retrieved 2016-01-10.
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