The backslash, \, is a typographical mark (glyph) used chiefly in computing. Sometimes called a reverse solidus, it is the mirror image of the common slash or solidus. It is also known as a slosh, according to the Macquarie dictionary, rev. 3rd edn (meaning #4).

On Unix systems, and in Unix-affiliated programming languages such as C and Perl, the backslash is used to indicate that the character following it should be treated specially. It is sometimes referred to as the escape character, though this risks confusion with the character generated by the Esc key.

On DOS and Microsoft Windows computer systems, the backslash is used as a delimiter for directory names in file paths. This is in contrast to Unix and other directory systems such as internet addresses, which use the slash for this purpose. The backslash was chosen for path delimiter because in an early version – which did not support directories and thus had no need for a path delimiter – the slash was used to introduce command-line options (which are prefixed by a hyphen ("-") in Unix systems).

This association with computing might explain why the forward slashes in URLs are commonly (and erroneously) read as backslashes.

In the TeX typesetting system, the backslash begins a markup tag.

In the GNU Emacs text editor, the backslash appears at the end of lines that wrap around to the next line.

In the Japanese equivalent of ASCII, the code point that would be used for backslash is instead a yen mark (¥), while on Korean computer keyboards, the backslash corresponds to the won symbol (₩ or W). Many Japanese environments nonetheless treat it like a backslash, causing confusion.

External links

• How ASCII Got Its Backslash The origin of the backslash character