Backspace () is the keyboard key that originally pushed the

typewriter A typewriter is a mechanical or electromechanical machine for typing characters. Typically, a typewriter has an array of keys, and each one causes a different single character to be produced on paper by striking an inked ribbon selectivel ...

carriage one position backwards and in modern computer systems moves the display cursor one position backwards,"Backwards" means to the left for left-to-right languages. deletes the character at that position, and shifts back the text after that position by one position.

Typewriter

In someMany typewriters don't advance accent characters, so that no backspace is needed. However, it is still used e.g. for combining "o" with "/". typewriters, a typist would, for example, type a lowercase letter A with acute accent (á) by typing a lowercase letter A, backspace, and then the acute accent key. This technique (also known as

overstrike In typography, overstrike is a method of printing characters that are missing from the printer's character set. The character is created by placing one character on another one — for example, overstriking "L" with "-" results in printing a " ...

) is the basis for such spacing modifiers in computer character sets such as the

ASCII ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because of ...

caret (^, for the

circumflex The circumflex () is a diacritic in the Latin and Greek scripts that is also used in the written forms of many languages and in various romanization and transcription schemes. It received its English name from la, circumflexus "bent around"a ...

accent). Backspace composition no longer works with typical modern digital displays or typesetting systems.There is no reason why a digital display or typesetting system could not be designed to allow backspace composition, a.k.a. overstrike, if an engineer chose to do that. As most contemporary computer display and typesetting systems are raster graphics-based rather than character-based (as of 2012), they make overstrike actually quite easy to implement. However, the use of proportional-width rather than fixed-width (monospaced) fonts makes the practical implementation of overstrike more complicated, and the original physical motivation for the technique is not present in digital computer systems. It has to some degree been replaced with the

combining diacritical mark In digital typography, combining characters are characters that are intended to modify other characters. The most common combining characters in the Latin script are the combining diacritical marks (including combining accents). Unicode al ...

s mechanism of

Unicode Unicode, formally The Unicode Standard,The formal version reference is is an information technology Technical standard, standard for the consistent character encoding, encoding, representation, and handling of Character (computing), text expre ...

, though such characters do not work well with many fonts, and precomposed characters continue to be used. Some software like

TeX Tex may refer to: People and fictional characters * Tex (nickname), a list of people and fictional characters with the nickname * Joe Tex (1933–1982), stage name of American soul singer Joseph Arrington Jr. Entertainment * ''Tex'', the Italian ...

Microsoft Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for serv ...

use the opposite method for diacritical marks, namely positioning the accent first, and then the base letter on its position.

Computers

Although the term "backspace" is the traditional name of the key which deletes the character to the left of the cursor, the actual key may be labeled in a variety of ways, for example ''delete'', ''Erase'' (for example in One Laptop Per Child), or with a left pointing arrow. A dedicated symbol for "backspace" exists as U+232B ⌫ but its use as a keyboard label is not universal. The backspace is distinct from the

delete key The delete key is a key on most computer keyboards which is typically used to delete either (in text mode) the character ahead of or beneath the cursor, or (in GUI mode) the currently-selected object. The key is sometimes referred to as the "fo ...

, which in paper media for computers would punch out all the holes to strike out a character, and in modern computers deletes text ''following'' it. Also, the delete key often works as a generic command to remove an object (such as an image inside a document, or a file in a

file manager A file manager or file browser is a computer program that provides a user interface to manage files and folders. The most common operations performed on files or groups of files include creating, opening (e.g. viewing, playing, editing or pr ...

), while backspace usually does not.

Common use

In modern systems, the backspace key is often mapped to the delete character (0x7f in ASCII or Unicode), although the backspace key's function of deleting the character before the cursor remains. The backspace key is commonly used to go back a page or up one level in graphical web or file browsers.

^H

Pressing the backspace key on a computer terminal would generate the

code 08, BS or Backspace, a

control code In computing and telecommunication, a control character or non-printing character (NPC) is a code point (a number) in a character set, that does not represent a written symbol. They are used as in-band signaling to cause effects other than th ...

which would delete the preceding character. That control code could also be accessed by pressing Control-H, as H is the eighth letter of the

Latin alphabet The Latin alphabet or Roman alphabet is the collection of letters originally used by the ancient Romans to write the Latin language. Largely unaltered with the exception of extensions (such as diacritics), it used to write English and the o ...

. Terminals which did not have the backspace code mapped to the function of moving the cursor backwards and deleting the preceding character would display the symbols ^H (

caret Caret is the name used familiarly for the character , provided on most QWERTY keyboards by typing . The symbol has a variety of uses in programming and mathematics. The name "caret" arose from its visual similarity to the original proofreade ...

, H) when the backspace key was pressed. Even if a terminal did interpret backspace by deleting the preceding character, the system receiving the text might not. Then, the sender's screen would show a message without the supposedly deleted text, while that text, and the deletion codes, would be visible to the recipient. This sequence is still used humorously for epanorthosis by computer literates, denoting the deletion of a pretended blunder, much like a strikethrough; in this case, however, the ^H symbol is faked by typing a regular '^' followed by typing a regular 'H'. Example: :''Be nice to this fool''^H^H^H^H''gentleman; he's visiting from corporate HQ.''Chapter 5. Hacker Writing Style
The

Jargon File The Jargon File is a glossary and usage dictionary of slang used by computer programmers. The original Jargon File was a collection of terms from technical cultures such as the MIT AI Lab, the Stanford AI Lab (SAIL) and others of the old ARPANET A ...

, version 4.4.7

^W and ^U

An alternative sometimes seen is ^W, which is the shortcut to delete the previous word in the Berkeley Unix terminal line discipline. This shortcut has also made it into the insert mode of the Vi text editor and its clone Vim. ^U deletes a line.

Other meanings

In a mainframe environment, ''to backspace'' means to move a

magnetic tape Magnetic tape is a medium for magnetic storage made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on the earlier magnetic wire recording from Denmark. Devices that use magne ...

backwards, typically to the previous block.

Notes

References

{{Keyboard keys Computer keys Control characters