Backspace
The backspace key is a key on the PC keyboard which, when pressed, moves the cursor one position to the left and removes the character located there. This corresponds to the function of the correction key on typewriters with correction function. It thus deletes in the opposite direction of the delete key. On keyboards, the key is often labelled ← or ⌫.
Most web browsers interpret the backspace key as "back" - that is, the page previously accessed in the history is called.
The control character for the backspace (BS) has the value 8 in ASCII and corresponds to ^H (Ctrl+H) in many terminals. In EBCDIC, BS has the value 16hex. If an ASCII terminal does not have the function to move the cursor to the left, ^H is output instead.
An extension of the backspace is (especially under Unix/Linux) ^W (Ctrl+W) or the combination Ctrl+Backspace (analogous to the combination Ctrl+Del), which can be used to delete the last word, i.e. all characters up to the last previous whitespace are removed. Furthermore, ^U (Ctrl+U) can be used to delete all previous characters of the current line. Some text editors like vim or emacs also offer this possibility.
Unicode contains the character ␈ (U+2408) as the symbol for the control character.
Backspace marked red
Alluding to the representation of the associated control character using ^H, internet forums sometimes start a word in a sentence and then "delete" it with a spelled-out "^H" to represent some sort of intentional Freudian slip:
Because I'm cowardly^H^H^H^Hcautious, just one harmless example.It shows what was actually meant, but then "deleted".
| Keys of an IBM/Windows keyboard (German/Austrian assignment "T1") | ||||||||||||||||||||||||
| Esc | F1 | F2 | F3 | F4 | F5 | F6 | F7 | F8 | F9 | F10 | F11 | F12 | Print | Rollers | PauseUntbr | Numeric keypad: | ||||||||
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| Insfg | Pos1 | Image ↑ | Num | - | |||||||||||||||||||
| Del | End | Image ↓ | 7 | 8 | 9 | + | ||||||||||||||||||
| 4 | 5 | 6 | ||||||||||||||||||||||
| ↑ | 1 | 2 | 3 | Enter | ||||||||||||||||||||
| ← | ↓ | → | , | |||||||||||||||||||||
Questions and Answers
Q: What is the backspace key?
A: The backspace key is a keyboard key (sometimes labeled as ←) that originally pushed the typewriter carriage one position backwards, and for modern computer screens, moves the cursor one position backwards, deletes the preceding character, and shifts back the text after it by one position.
Q: How was backspace composition used in typewriters?
A: In typewriters, a typist would type a lowercase letter "a" with acute accent (á) by typing a lowercase letter "a" then backspace, and then the acute accent key (also known as overstrike). This is the basis for such spacing modifiers in computer character sets such as the ASCII caret (^).
Q: How has backspace composition been replaced?
A: Backspace composition has been replaced with the combining diacritical marks mechanism of Unicode, though such characters do not work well with many fonts, and precomposed characters continue to be used. Some software like TeX or Microsoft Windows use the opposite method for diacritical marks.
Q: What does pressing the backspace key on a computer terminal generate?
A: Pressing the backspace key on a computer terminal generates an ASCII code 08 or BS which stands for Backspace - this control code will delete any preceding character.
Q: What is ^H commonly used for?
A: ^H is commonly used humorously for epanorthosis by computer literates denoting deletion of a pretended blunder much like a strikethrough.
Q: How does ^W differ from ^H?
A: ^W is a shortcut to delete an entire word while ^H only deletes one character at time.
Q: What are some other shortcuts related to deleting text? A: For more extensive deletions than just individual characters or words there are shortcuts like ^U which kills an entire line of text.
