In
computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, hardware and softw ...
, a modifier key is a special key (or combination) on a
computer keyboard
A computer keyboard is a built-in or peripheral input device modeled after the typewriter keyboard which uses an arrangement of buttons or Push-button, keys to act as Mechanical keyboard, mechanical levers or Electronic switching system, electro ...
that temporarily modifies the normal action of another key when pressed together. By themselves, modifier keys usually do nothing; that is, pressing any of the , , or keys alone does not (generally) trigger any action from the computer. They are commonly used in defined sequences of keys with another keys to trigger a specific action. These sequences are called
keyboard shortcuts
In computing, a keyboard shortcut (also hotkey/hot key or key binding) is a software-based assignment of an action to one or more keys on a computer keyboard. Most Operating system, operating systems and Application software, applications come ...
.
For example, in most
keyboard layout
A keyboard layout is any specific physical, visual, or functional arrangement of the keys, legends, or key-meaning associations (respectively) of a computer keyboard, mobile phone, or other computer-controlled typographic keyboard. Standard keybo ...
s the Shift key combination will produce a capital letter "A" instead of the default lower-case letter "a" (unless in
Caps Lock or
Shift lock mode). A combination of in
Microsoft Windows
Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...
will trigger the shortcut for closing the
active window; in this instance, Alt is the modifier key. In contrast, pressing just or will probably do nothing unless assigned a specific function in a particular program (for example, activating input aids or the toolbar of the active window in Windows).
User interface
In the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine fro ...
expert
Jef Raskin coined the term "
quasimode" to describe the state a computer enters into when a modifier key is pressed.
History
Modifier keys on personal computers
The most common are:
*
* (Control)
* (Alternate) – also labelled on
Apple keyboards.
* (Alternate Graphic)
* – Meta key, found on MIT, Symbolics, and Sun Microsystems keyboards.
* – Hyper key, found on the
Space-cadet keyboard
* – Super key, found on MIT, Symbolics, Linux, and BSD keyboards.
* (Windows logo) – found on Windows keyboards.
* – Command key, found on Apple keyboards. On older keyboards labelled (Apple logo).
* (Function) – often present on small-layout keyboards, or keyboard where the top row of function keys have multimedia functions like controlling volume attached.
The (Sun) Meta key, Windows key, (Apple) Cmd key, and the analogous "Amiga key" () on
Amiga
Amiga is a family of personal computers produced by Commodore International, Commodore from 1985 until the company's bankruptcy in 1994, with production by others afterward. The original model is one of a number of mid-1980s computers with 16-b ...
computers, are usually handled equivalently. Under the Linux operating system, the desktop environment
KDE
KDE is an international free software community that develops free and open-source software. As a central development hub, it provides tools and resources that enable collaborative work on its projects. Its products include the KDE Plasma gra ...
calls this key
Meta, while
GNOME
A gnome () is a mythological creature and diminutive spirit in Renaissance magic and alchemy, introduced by Paracelsus in the 16th century and widely adopted by authors, including those of modern fantasy literature. They are typically depict ...
calls this key, neutrally,
Super
Super may refer to:
Computing
* SUPER (computer program), or Simplified Universal Player Encoder & Renderer, a video converter/player
* Super (computer science), a keyword in object-oriented programming languages
* Super key (keyboard butto ...
. This could be considered confusing, since the original
space-cadet keyboard and the
X Window System
The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like operating systems.
X originated as part of Project Athena at Massachusetts Institute of Technology (MIT) in 1984. The X protocol has been at ...
recognize a "" modifier distinct from "".
The
ZX Spectrum
The ZX Spectrum () is an 8-bit computing, 8-bit home computer developed and marketed by Sinclair Research. One of the most influential computers ever made and one of the all-time bestselling British computers, over five million units were sold. ...
has a Symbol Shift key in addition to Caps Shift. This was used to access additional punctuation and keywords.
The
MSX
MSX is a standardized home computer architecture, announced by ASCII Corporation on June 16, 1983. It was initially conceived by Microsoft as a product for the Eastern sector, and jointly marketed by Kazuhiko Nishi, the director at ASCII Corpo ...
computer keyboard, besides Shift and Control, also included two special modifier keys, Code and Graph. In some models, as in the Brazilian
Gradiente Expert, the Code and Graph keys are labelled "" and "" (Left and Right Graphics). They are used to select special graphic symbols and extended characters.
Likewise, the
Commodore 64
The Commodore 64, also known as the C64, is an 8-bit computing, 8-bit home computer introduced in January 1982 by Commodore International (first shown at the Consumer Electronics Show, January 7–10, 1982, in Las Vegas). It has been listed in ...
and other Commodore computers had the Commodore key at the bottom left of the keyboard.
Compact keyboards, such as those used in
laptop
A laptop computer or notebook computer, also known as a laptop or notebook, is a small, portable personal computer (PC). Laptops typically have a Clamshell design, clamshell form factor (design), form factor with a flat-panel computer scree ...
s, often have a
Fn key to save space by combining two functions that are normally on separate keys. On laptops, pressing plus one of the function keys, e.g., F2, often control hardware functions. Keyboards that lack a dedicated numeric keypad may mimic its functionality by combining the Fn key with other keys.
The
MIT
The Massachusetts Institute of Technology (MIT) is a private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of modern technology and sc ...
space-cadet keyboard had additional Top and Front modifier keys. Combined with standard modifiers, it could enter as many as 8,000 different characters.
Specialist typesetting machines, and word processors such as the
Redactron, sometimes used multiple modifier keys to trigger mode changes e.g. for emboldened text or justification changes. This approach gradually became obsolete after software based on commodity hardware and operating systems adopted the
WIMP
WiMP is a music streaming service available on mobile devices, tablets, network players and computers. WiMP, standing for "Wireless Music Player," was a music streaming service that emphasized high-quality audio. WiMP offered music and podcast ...
metaphor which provided drop-down menus etc.
Accented characters
Some non-English language keyboards have special keys to produce
accented modifications of the standard Latin-letter keys. In fact, the standard British
keyboard layout
A keyboard layout is any specific physical, visual, or functional arrangement of the keys, legends, or key-meaning associations (respectively) of a computer keyboard, mobile phone, or other computer-controlled typographic keyboard. Standard keybo ...
includes an accent key on the top-left corner to produce àèìòù, although this is a two step procedure, with the user pressing the accent key, releasing, then pressing the letter key. These kinds of keys are called
dead key
A dead key is a special kind of modifier key on a mechanical typewriter, or computer keyboard, that is typically used to attach a specific diacritic to a base letter (alphabet), letter. The dead key does not generate a (complete) grapheme, charact ...
s. The
AltGr modifier produces the áéíóú sequence, or in conjunction with the Shift key, ÁÉÍÓÚ. Keyboards of some languages simply include the accented characters on their own keys. Some keyboards also have a
Compose key
A compose key (sometimes called multi key) is a key on a computer keyboard that indicates that the following (usually 2 or more) keystrokes trigger the insertion of an alternate character, typically a precomposed character or a symbol.
For insta ...
for typing accented and other special characters. By pressing , and then two other keys, something similar to a combination of the glyphs of the two previous keys will appear on the screen.
Modifier Only
It is possible to use a modifier key as a normal key.
In 2005
Quicksilver (software) introduced a feature called 'Modifier-only Activation'. If a modifier key (Command) was pressed for a short duration (under 300ms) then released with no other key being pressed, this was taken as a 'trigger'.
In 2012 this kind of use of a Modifier key appeared in Apple's 'Dictation preferences' under
OS X Mountain Lion
OS X Mountain Lion (version 10.8) is the ninth major release of macOS, Apple Inc.'s desktop and server operating system for Macintosh computers. OS X Mountain Lion was released on July 25, 2012, for purchase and download through the Mac App S ...
, where Apple introduced options like 'Press Right Command Key twice' to launch dictation.
This functionality was further increased in macOS Sequoia (2024) with the addition of modifier only keys to be used alone to activate shortcuts such as 'Show Desktop, including Left Command, Left Option, Left Control, Left Shift, Right Command, Right Control, Right Option, Right Shift, fn. This effectively gives users 9 extra keys to activate shortcuts.
Dual-role keys
It is also possible to use (with some utility software) one key both as a normal key and as a modifier.
For example, you can use the both as a normal Space bar and as a Shift. Intuitively, it will act as a standard Space when you want a whitespace, and a Shift when you want it to act as a shift. I.e. when you simply press and release it, it is the usual space, but when you press other keys, say , and , while holding down the , then they will be treated as plus X, Y and Z.
The above example is known as "SandS", standing for "Space and Shift" in Japan. But any number of any combinations are possible.
To press shift+space in the previous example, you need in addition to a space/shift dual role key, one of (a) another space/shift key, (b) a usual shift, or (c) a usual space key.
See also
*
Bucky bit
*
Control character
In computing and telecommunications, a control character or non-printing character (NPC) is a code point in a character encoding, character set that does not represent a written Character (computing), character or symbol. They are used as in-ba ...
*
Function key
A function key is a key on a computer or computer terminal, terminal computer keyboard, keyboard that can be programmed to cause the operating system or an application program to perform certain actions, a form of soft key. On some keyboards/com ...
*
Keyboard layout
A keyboard layout is any specific physical, visual, or functional arrangement of the keys, legends, or key-meaning associations (respectively) of a computer keyboard, mobile phone, or other computer-controlled typographic keyboard. Standard keybo ...
*
Space-cadet keyboard
*
Table of keyboard shortcuts
*
Emacs pinky -
repetitive strain injury
A repetitive strain injury (RSI) is an injury to part of the musculoskeletal or nervous system caused by repetitive use, vibrations, compression or long periods in a fixed position. Other common names include repetitive stress injury, repetitiv ...
developed by too much use of control key, notably for
Emacs
Emacs (), originally named EMACS (an acronym for "Editor Macros"), is a family of text editors that are characterized by their extensibility. The manual for the most widely used variant, GNU Emacs, describes it as "the extensible, customizable, s ...
users.
References
External links
Bucky bits in the Jargon file
{{DEFAULTSORT:Modifier Key
Computer keys
User interface techniques
de:Tastenkombination#Hilfstasten für Tastenkombinationen