Asterisk

An asterisk (*) is a typographical symbol or glyph. It is so called because it resembles a star, (Latin astra). In some computer circles it is called a splat, perhaps due to the "squashed-bug" appearance of the asterisk on many early line printers. Computer scientists often pronounce it as star (as, for example, in the A* algorithm).

Uses of the asterisk include:

In written text, the asterisk is used to call out a footnote or otherwise mark something.
In linguistics, an asterisk next to a word may represent a nonstandard usage or a historically reconstructed word.
In computing, the asterisk is sometimes used as a wildcard, meaning that it stands for zero or more unspecified characters (the Kleene star)
In mathematics, it signifies the complex conjugate of a complex number, e.g. if x=a+ib, x*=a-ib
Many programming languages and calculators use the asterisk as a symbol for multiplication.
In Unix and Perl, the asterisk is often used as a Kleene star, which means it stands for zero or more copies of the preceding regular expression.
On a Touch-Tone telephone keypad, * (called star) is one of the two special keys, and is found on the left of the zero. (The other is the number sign (or pound or hash key.)
In many instant message communication programs (such as AOL Instant Messenger and Yahoo! Messenger), chat rooms, and message boards, it is placed at the beginning of a line correcting a typographical error.
Some e-mail and instant messenger users place asterisks around a word or phrase for emphasis (as opposed to using all caps, which signifies shouting and is considered rude).
In cricket, it signifies a total number of runs scored by a batsman without losing his wicket, e.g. 107* means '107 not out'.
In the GCSE examination, A* is a special top grade that is distinguised from grade A.

In fine mathematical typography the Unicode character U+2217 (∗) "math asterisk" is available. This character, also appeared in the position of the regular asterisk in the PostScript symbol character set in the Symbol font included with Windows and Macintosh operating systems and with many printers. It should be used in fine typography for a large asterisk that lines up with the other mathematical operators.

A group of three asterisks arranged in a trianglular formation is called an asterism.

In computer programming, the asterisk corresponds to Unicode and ASCII character 42, or 0x002A.

Unicode also encodes "two asterisks aligned vertically" as the character U+2051. The asterism is encoded as U+2042.

Not to be confused with Asterix, the character of children's comic books.

Asterisk is also an open source PBX running on Linux.

External links

The Asterisk PBX home page