Esc key

For other uses, see ESC.

Not to be confused with Escape character.

A computer keyboard with the Esc key in the top-left corner

IBM 83-key keyboard (1981), with Esc in the top-left corner of the alphanumeric section

On computer keyboards, the Esc key Esc (named Escape key in the international standard series ISO/IEC 9995) is a key used to generate the escape character (which can be represented as ASCII code 27 in decimal, Unicode U+001B, or Ctrl+[). The escape character, when sent from the keyboard to a computer, often is interpreted by software as "stop", "cancel" or "exit", and when sent from the computer to an external device (including many printers since the 1980s, computer terminals and Linux consoles, for example) marks the beginning of an escape sequence to specify operating modes or characteristics generally.

It is now generally placed at the top left corner of the keyboard, a convention dating at least to the original IBM PC keyboard, though the key itself originated decades earlier with teletypewriters.

Symbol

ISO keyboard symbol for "Escape"

The keyboard symbol for the ESC key (which may be used when the usual Latin lettering "Esc" is not preferred for labelling the key) is standardized in ISO/IEC 9995-7 as symbol 29, and in ISO 7000 "Graphical symbols for use on equipment" as symbol ISO-7000-2029. This symbol is encoded in Unicode as U+238B broken circle with northwest arrow (⎋).

Origins

The name of the equivalent key on some early Teletype Model 33 keyboards was labeled Alt Mode..., the alternative mode of operation causing the escapement to treat the following one character in a special way. Much later printers and computer terminals that would use escape sequences often would take more than one following byte as part of a special sequence.

Uses

As most computer users are no longer concerned with the details of controlling their computer's peripherals, the task for which the escape sequences were originally designed, the escape key was appropriated by application programmers, most often to mean Stop. This use continues today in Microsoft Windows's method of escape as a shortcut in dialog boxes for No, Quit, Exit, Cancel, or Abort, as well as a common shortcut key for the Stop button in many web browsers, and to cancel drag and drop operations.

On machines running Microsoft Windows, prior to the implementation of the Windows key on keyboards, the typical practice for invoking the "start" button was to hold down the Control key and press escape. This key combination still works as of Windows 10.

Microsoft Windows makes use of "Esc" for many key shortcuts. Many of these shortcuts have been present since Windows 3.0, through Windows XP and later.

In macOS, "Esc" usually closes or cancels a dialog box or sheet. The ⌘ Command+⌥ Option+⎋ Esc combination opens the Force Quit dialog box, allowing users to end non-responsive applications. Another use for the Esc key, in combination with the Command key, is switching to Front Row, if installed.

In most computer games, the escape key is used as a pause button and/or as a way to bring up the in-game menu, usually containing ways to exit the program. This is despite the existence of a separate Pause/Break key.

ADM-3A keyboard layout used in vi development, with escape in what is now the tab position

In the vi family of text editors, escape is used to switch modes. This usage is due to escape being conveniently placed in what is now the tab position on the ADM-3A terminal keyboard used to develop vi, though it is now inconveniently placed. This is similar to how the extensive modifier keys in Emacs were easily used on the original keyboard (the space-cadet keyboard), being placed together, but these keys have now been spread around the keyboard, becoming more difficult to use.

The TECO editor uses ESCape as a delimiter when used once, and as an execute key when used twice in a row.

Escape sequences on KSR terminals

Old keyboard Send/Receive (KSR) printers, and visual display units (VDUs), would normally be controlled by escape sequences sent by the computer to the peripheral device, but there were situations where these devices could be used "off-line" with the keyboard effectively connected to the output device, and so the need could arise to type escape sequences "by hand" to control the peripheral. Although such devices are long out of use, standard processing of ANSI Escape sequences very similar to the 1970s VT100, is implemented in both ANSI.SYS and other more modern pseudo-terminal interfaces used in Unix-like environments, one example being Linux consoles, meaning newer, higher-level abstractions haven't changed the fact that typing the escape key followed by something like the six characters [32;1m affects subsequently text in output, in this case turning it green.

References

IBM PC keyboard (Windows, ANSI US layout)
Esc		F1	F2	F3	F4		F5	F6	F7	F8		F9	F10	F11	F12		PrtScn/ SysRq	Scroll Lock	Pause/ Break
<imagemap> File:KB United States-NoAltGr.svg|450px desc none # Row are 60 pixel tall in reference to the unsized original # rect left top right bottom [[link]] # Top row shift rect 0 0 60 30 Tilde rect 60 0 120 30 Exclamation mark rect 120 0 180 30 At sign rect 180 0 240 30 Number sign rect 240 0 300 30 Dollar sign rect 300 0 360 30 Percent sign rect 360 0 420 30 Caret rect 420 0 480 30 Ampersand rect 480 0 540 30 Asterisk rect 540 0 600 30 Parenthesis rect 600 0 660 30 Parenthesis rect 660 0 720 30 Underscore rect 720 0 780 30 Plus sign rect 780 0 900 30 Backspace Top row rect 0 0 60 60 backtick rect 60 0 120 60 1 (number) rect 120 0 180 60 2 (number) rect 180 0 240 60 3 (number) rect 240 0 300 60 4 (number) rect 300 0 360 60 5 (number) rect 360 0 420 60 6 (number) rect 420 0 480 60 7 (number) rect 480 0 540 60 8 (number) rect 540 0 600 60 9 (number) rect 600 0 660 60 0 rect 660 0 720 60 Hyphen-minus rect 720 0 780 60 Equals sign rect 780 0 900 60 Backspace Second row shift rect 0 61 90 90 Tab key rect 90 61 150 90 Q rect 150 61 210 90 W rect 210 61 270 90 E rect 270 61 330 90 R rect 330 61 390 90 T rect 390 61 450 90 Y rect 450 61 510 90 U rect 510 61 570 90 I rect 570 61 630 90 O rect 630 61 690 90 P rect 690 61 750 90 Curly bracket rect 750 61 810 90 Curly bracket rect 810 61 900 90 Vertical bar Second row rect 0 61 90 120 Tab key rect 90 61 150 120 q rect 150 61 210 120 w rect 210 61 270 120 e rect 270 61 330 120 r rect 330 61 390 120 t rect 390 61 450 120 y rect 450 61 510 120 u rect 510 61 570 120 i rect 570 61 630 120 o rect 630 61 690 120 p rect 690 61 750 120 Square bracket rect 750 61 810 120 Square bracket rect 810 61 900 120 Backslash Third row shift rect 0 121 105 150 Caps lock rect 105 121 165 150 A rect 165 121 225 150 S rect 225 121 285 150 D rect 285 121 345 150 F rect 345 121 405 150 G rect 405 121 465 150 H rect 465 121 525 150 J rect 525 121 585 150 K rect 585 121 645 150 L rect 645 121 705 150 Colon (punctuation) rect 705 121 765 150 Quotation mark rect 765 121 900 150 Enter key Third row rect 0 121 105 180 Caps lock rect 105 121 165 180 a rect 165 121 225 180 s rect 225 121 285 180 d rect 285 121 345 180 f rect 345 121 405 180 g rect 405 121 465 180 h rect 465 121 525 180 j rect 525 121 585 180 k rect 585 121 645 180 l rect 645 121 705 180 Semicolon rect 705 121 765 180 Apostrophe rect 765 121 900 180 Enter key Fourth row shift rect 0 181 135 210 Shift key rect 135 181 195 210 Z rect 195 181 255 210 X rect 255 181 315 210 C rect 315 181 375 210 V rect 375 181 435 210 B rect 435 181 495 210 N rect 495 181 555 210 M rect 555 181 615 210 Bracket rect 615 181 675 210 Bracket rect 675 181 735 210 Question mark rect 735 181 900 210 Shift key Fourth row rect 0 181 135 240 Shift key rect 135 181 195 240 z rect 195 181 255 240 x rect 255 181 315 240 c rect 315 181 375 240 v rect 375 181 435 240 b rect 435 181 495 240 n rect 495 181 555 240 m rect 555 181 615 240 Comma (punctuation) rect 615 181 675 240 Full stop rect 675 181 735 240 Slash (punctuation) rect 735 181 900 240 Shift key Bottom row rect 0 241 90 300 Control key rect 90 241 150 300 Windows key rect 150 241 240 300 Alt key rect 240 241 600 300 Space bar rect 600 241 690 300 Alt key rect 690 241 750 300 Windows key rect 750 241 810 300 Menu key rect 810 241 900 300 Control key </imagemap>																	Insert	Home	PgUp		Num Lock	∕	∗	−
																	Delete	End	PgDn		7	8	9	+
																					4	5	6
																		↑			1	2	3	Enter
																	←	↓	→		0    Ins		.  Del