Backspace is the keyboard key that originally pushed the typewriter

Typewriter

A typewriter is a mechanical or electromechanical device with keys that, when pressed, cause characters to be printed on a medium, usually paper. Typically one character is printed per keypress, and the machine prints the characters by making ink impressions of type elements similar to the pieces...

 carriage one position backwards, and in modern computer displays moves the cursor one position backwards, deletes the preceding character, and shifts back the text after it by one position.

In 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 (also known as overstrike

Overstrike

In typography, overstrike is a method of printing characters that are missing from the printer's character set. It was widely used around the early 1990s...

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

ASCII

The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...

 caret (^, for the circumflex accent). Backspace composition no longer works with digital displays or typesetting systems. It has to some degree been replaced with the combining diacritical marks mechanism of Unicode

Unicode

Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...

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

TeX

TeX is a typesetting system designed and mostly written by Donald Knuth and released in 1978. Within the typesetting system, its name is formatted as ....

 or Microsoft Windows

Microsoft Windows

Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

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

Pressing the backspace key on a computer terminal would generate the ASCII

ASCII

The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...

 code 08, BS or Backspace, a control code which would delete the preceding character. That control code could also be accessed by pressing Control-H, as H

H

H .) is the eighth letter in the basic modern Latin alphabet.-History:The Semitic letter ⟨ח⟩ most likely represented the voiceless pharyngeal fricative . The form of the letter probably stood for a fence or posts....

 is the eighth letter of the Latin alphabet

Latin alphabet

The Latin alphabet, also called the Roman alphabet, is the most recognized alphabet used in the world today. It evolved from a western variety of the Greek alphabet called the Cumaean alphabet, which was adopted and modified by the Etruscans who ruled early Rome...

. 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, H — see Caret notation

Caret notation

Caret notation is a notation for unprintable control characters in ASCII encoding. The notation consists of a caret followed by a capital letter; this digraph stands for the ASCII code that has the numerical value equivalent to the letter's numerical value. For example the EOT character with a...

) when the backspace key was pressed. This sequence is still used humorously for epanorthosis

Epanorthosis

An epanorthosis is a figure of speech that signifies emphatic word replacement. The example "thousands, no, millions!" is a stock example. More often, however, epanorthosis signifies immediate and emphatic self-correction, and as such often follows a Freudian slip .Examples:*"The psychologist known...

 by computer literates, denoting the deletion of a pretended blunder, much like a strikethrough

Strikethrough

Strikethrough is a typographical presentation of words with a horizontal line through their center. This is an example....

.

Example:

My slave-dri^H^H^H^H^H^H^H^H^Hboss decided to stall the project.

A more concise alternative sometimes seen is ^W, which is the shortcut to delete the previous word in the Berkeley Unix terminal line discipline. One ^W can replace a whole string of ^H's. This shortcut has also made it into the Vi

Vi

vi is a screen-oriented text editor originally created for the Unix operating system. The portable subset of the behavior of vi and programs based on it, and the ex editor language supported within these programs, is described by the Single Unix Specification and POSIX.The original code for vi...

 text editor. For really embarrassing blunders, ^U (kill line) can outdo a series of ^W.

The backspace is distinct from the delete key

Delete key

The delete key , known less ambiguously as forward delete, performs a function when struck on a computer keyboard during text or command editing, which is to discard the character ahead of the cursor's position, moving all following characters one position "back" towards the freed letterspace. The...

, 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

File manager

A file manager or file browser is a computer program that provides a user interface to work with file systems. The most common operations performed on files or groups of files are: create, open, edit, view, print, play, rename, move, copy, delete, search/find, and modify file attributes, properties...

), while backspace usually has no effect.

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.

In a mainframe

Mainframe computer

Mainframes are powerful computers used primarily by corporate and governmental organizations for critical applications, bulk data processing such as census, industry and consumer statistics, enterprise resource planning, and financial transaction processing.The term originally referred to the...

 environment, to backspace means to move a magnetic tape

Magnetic tape

Magnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...

 backwards, typically to the previous block.

The backspace key is commonly used to go back a page when exploring folders in graphical environments, or when browsing the Web

World Wide Web

The World Wide Web is a system of interlinked hypertext documents accessed via the Internet...

 in web browser

Web browser

A web browser is a software application for retrieving, presenting, and traversing information resources on the World Wide Web. An information resource is identified by a Uniform Resource Identifier and may be a web page, image, video, or other piece of content...

s.

Although the term "backspace" is the standard name of the key which deletes the character to the left of the cursor, the actual key may be labelled in a variety of ways, for example delete, Erase (for example in One Laptop Per Child), or with a left pointing arrow.