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An asterisk (*) is a typographical symbol or glyph. It is so called because it resembles a conventional image of a star, (Latin astra). Computer scientists often pronounce it as star (as, for example, in the A* algorithm).

The asterisk derives from the need of the printers of family trees in feudal times for a symbol to indicate date of birth. The original shape was six-armed, each arm like a teardrop shooting from the center. For this reason, in some computer circles it is called a splat, perhaps due to the "squashed-bug" appearance of the asterisk on many early line printers.

In this form the character appeared in typewriters. However, some typewriters had difficulty printing the six arms distinctly. Further, as the Arab-Israeli difficulties drew on, Arabs would not buy typewriters with a six-armed symbol, which they identified with the Star of David used by the Israelis. Hence many systems use a five-armed symbol, which is referred to as the "Arabic star", which was given a distinct character in Unicode, "ARABIC FIVE POINTED STAR" (U+066D).

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 computer science, the asterisk is used in regular expressions to denote zero or more repetitions of a pattern; this use is known as the Kleene star or Kleene closure after Stephen Kleene.
• In some computer interfaces, such as the Unix shell and Microsoft's Command Prompt, the asterisk is the wildcard character and stands for any string.
• Many programming languageAn alternate rewrite has been has been. Please refer to it for large rewrites. A programming language or computer language is a standardized communication technique for expressing instructions to a computer. It is a set of syntactic and semantic rules uses and calculatorA calculator is a device for performing numerical calculations. It should not be confused with a calculating machine. Nowadays many people have a calculator with them as part of their mobile phone and/or personal digital assistant. Engineers and accountans use the asterisk as a symbol for multiplicationArithmetic In its simplest form, multiplication is a quick way of adding identical numbers. The result of multiplying numbers is called a product''. The numbers being multiplied are called coefficients or factors and individually as the multiplicand and m. In the C programming languageThe C Programming Language Brian Kernighan and Dennis Ritchie, the original edition that served for many years as an informal specification of the language The C programming language is a low-level standardized programming language developed in the early, the asterisk is used to get the contents of a pointerThis article is about the computer data type. For other meanings of pointer see pointer (disambiguation). In computer science, a pointer is a programming language datatype whose value is used to refer to ("points to") another value stored elsewhere in the; it is the inverse of the & operator which gives the address of a variable. It is also used declare a pointer variable.
• In the Unified Modelling Language, the asterisk is used to denote zero to many classes.
• In mathematicsMathematics is commonly defined as the study of patterns of structure, change, and space; more informally, one might say it is the study of "figures and numbers". In the formalist view, it is the investigation of axiomatically defined abstract structures, it signifies the complex conjugateIn mathematics, the complex conjugate of a complex number is given by changing the sign of the imaginary part. Thus, the conjugate of the complex number z a + ib (where a and b are real numbers) is defined to be z a − ib''. It is also often denoted of a complex number, e.g. if x=a+ib, x*=a-ib
• 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 ("pound" or "hash")).
• 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 distinguished from grade A.

In fine mathematical typography the Unicode character U+2217 (∗) "math asterisk" is available (HTML entity ∗). 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 triangular formation is called an asterism.