Backspace key

Backspace is the keyboard key that originally pushed the typewriter carriage one position backwards, and in modern computer systems moves the display cursor one position backwards, deletes the character at that position, and shifts back the text after that position by one position.

In some 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) is the basis for such spacing modifiers in computer character sets such as the ASCII caret (^, for the circumflex accent). Backspace composition no longer works with typical modern digital displays or typesetting systems It has to some degree 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, namely positioning the accent first, and then the base letter on its position.

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 moderately rare.

The backspace is distinct from the delete key, 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), while backspace usually does not.

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.

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