The asterisk ( ), from
Late Latin
Late Latin is the scholarly name for the form of Literary Latin of late antiquity.Roberts (1996), p. 537. English dictionary definitions of Late Latin date this period from the 3rd to 6th centuries CE, and continuing into the 7th century in ...
, from
Ancient Greek
Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...
, , "little star", is a
typographical symbol. It is so called because it resembles a conventional image of a
heraldic star.
Computer scientists and
mathematicians often vocalize it as star (as, for example, in ''the
A* search algorithm'' or ''
C*-algebra''). An asterisk is usually five- or six-pointed in
print and six- or eight-pointed when handwritten, though more complex forms exist. Its most common use is to call out a
footnote. It is also often used to censor offensive words.
In
computer science
Computer science is the study of computation, information, and automation. Computer science spans Theoretical computer science, theoretical disciplines (such as algorithms, theory of computation, and information theory) to Applied science, ...
, the asterisk is commonly used as a
wildcard character, or to denote
pointers, repetition, or
multiplication
Multiplication is one of the four elementary mathematical operations of arithmetic, with the other ones being addition, subtraction, and division (mathematics), division. The result of a multiplication operation is called a ''Product (mathem ...
.
History

The asterisk was already in use as a symbol in
ice age cave paintings. There is also a two-thousand-year-old character used by
Aristarchus of Samothrace called the , , which he used when proofreading Homeric poetry to mark lines that were duplicated.
Origen
Origen of Alexandria (), also known as Origen Adamantius, was an Early Christianity, early Christian scholar, Asceticism#Christianity, ascetic, and Christian theology, theologian who was born and spent the first half of his career in Early cent ...
is known to have also used the asteriskos to mark missing
Hebrew
Hebrew (; ''ʿÎbrit'') is a Northwest Semitic languages, Northwest Semitic language within the Afroasiatic languages, Afroasiatic language family. A regional dialect of the Canaanite languages, it was natively spoken by the Israelites and ...
lines from his
Hexapla
''Hexapla'' (), also called ''Origenis Hexaplorum'', is a Textual criticism, critical edition of the Hebrew Bible in six versions, four of them translated into Ancient Greek, Greek, preserved only in fragments. It was an immense and complex wor ...
. The asterisk evolved in shape over time, but its meaning as a symbol used to correct defects remained.
In the Middle Ages, the asterisk was used to emphasize a particular part of text, often linking those parts of the text to a marginal comment. However, an asterisk was not always used.
One hypothesis to the origin of the asterisk is that it stems from the 5000-year-old
Sumerian character
dingir, , though this hypothesis seems to only be based on visual appearance.
Usage
Censorship
When toning down
expletives, asterisks are often used to replace letters. For example, the word "badword" might become "ba***rd", "b*****d", "b******" or even "*******". Vowels tend to be censored with an asterisk more than consonants, but the intelligibility of censored profanities with multiple syllables such as "b*dw*rd" and "b*****d" or "ba****d", or uncommon ones is higher if put in context with surrounding text.
When a document containing
classified information is published, the document may be
"sanitized" (
redacted) by replacing the classified information with asterisks. For example, the
Intelligence and Security Committee Russia report.
Competitive sports and games
In colloquial usage, an asterisk attached to a sporting
record indicates that it is somehow tainted. This is because results that have been considered dubious or set aside are recorded in the record books with an asterisk rendering to a footnote explaining the reason or reasons for concern.
Baseball
The usage of the term in sports arose during the 1961 baseball season in which
Roger Maris of the
New York Yankees
The New York Yankees are an American professional baseball team based in the Boroughs of New York City, New York City borough of the Bronx. The Yankees compete in Major League Baseball (MLB) as a member club of the American League (AL) Am ...
was threatening to break
Babe Ruth's 34-year-old single-season
home run record. Ruth had amassed 60 home runs in a season with only 154 games, but Maris was playing the first season in the American League's newly expanded 162-game season. Baseball Commissioner
Ford C. Frick, a friend of Ruth's during the legendary slugger's lifetime, held a press conference to announce his "ruling" that should Maris take longer than 154 games both records would be acknowledged by Major League Baseball, but that some "distinctive mark"
is termref name=Salon> be placed next to Maris', which should be listed alongside Ruth's achievement in the "record books". The asterisk as such a mark was suggested at that time by
New York Daily News
The ''Daily News'' is an American newspaper based in Jersey City, New Jersey. It was founded in 1919 by Joseph Medill Patterson in New York City as the ''Illustrated Daily News''. It was the first U.S. daily printed in Tabloid (newspaper format ...
sportswriter
Dick Young, not Frick.
[ The reality, however, was that MLB actually had no direct control over any record books until many years later, and it all was merely a suggestion on Frick's part. Within a few years the controversy died down and all prominent baseball record keepers listed Maris as the single-season record holder for as long as he held the record.][
Nevertheless, the stigma of holding a tainted record remained with Maris for many years, and the concept of a real or figurative asterisk denoting less-than-accepted "official" records has become widely used in sports and other competitive endeavors. A 2001 TV movie about Maris's record-breaking season was called '' 61*'' (pronounced ''sixty-one asterisk'') in reference to the controversy.
Uproar over the integrity of baseball records and whether or not qualifications should be added to them arose again in the late 1990s, when a steroid-fueled power explosion led to the shattering of Maris' record. Even though it was obvious - and later admitted - by Mark McGwire that he was heavily on steroids when he hit 70 home runs in 1998, ruling authorities did nothing - to the annoyance of many fans and sportswriters. Three years later self-confessed steroid-user Barry Bonds pushed that record out to 73, and fans once again began to call for an asterisk in the sport's record books.
Fans were especially critical and clamored louder for baseball to act during the 2007 season, as Bonds approached and later broke Hank Aaron's career home run record of 755.
The ]Houston Astros
The Houston Astros are an American professional baseball team based in Houston. The Astros compete in Major League Baseball (MLB) as a member club of the American League (AL) American League West, West Division. They are one of two major leag ...
' 2017 World Series win was marred after an investigation by MLB revealed the team's involvement in a sign-stealing scheme during that season. Fans, appalled by what they perceived to be overly lenient discipline against the Astros players, nicknamed the team the "Houston Asterisks".
In recent years, the asterisk has come into use on baseball scorecards to denote a "great defensive play."
Usage in anti-doping campaigns
*By the end of the first decade of the 21st century, the association of baseball and its records with doping had become so notorious that the term "asterisk" had become firmly associated with doping in sport. In February 2011 the United States Olympic Committee and the Ad Council launched an anti-steroid campaign called "Play Asterisk Free" aimed at teens. The campaign, whose logo uses a heavy asterisk (✱), first launched in 2008 under the name "Don't Be An Asterisk".
Cricket
* In cricket
Cricket is a Bat-and-ball games, bat-and-ball game played between two Sports team, teams of eleven players on a cricket field, field, at the centre of which is a cricket pitch, pitch with a wicket at each end, each comprising two Bail (cr ...
, it signifies a total number of runs scored by a batsman without losing their wicket; e.g. "107*" means "107 not out".
* Where only the scores of the two batsmen that are currently in are being shown, an asterisk following a batsman's score indicates that he is due to face the next ball to be delivered.
* When written before a player's name on a scorecard, it indicates the captain of the team.
* It is also used on television when giving a career statistic during a match. For example, "47*" in a number of matches column means that the current game is the player's 47th.
Other sports
During the first decades of the 21st century, the term ''asterisk'' to denote a tainted accomplishment caught on in other sports first in North America and then, due in part to North American sports' widespread media exposure, around the world.
Computing
* In regular expressions, the asterisk is used to denote zero or more repetitions of a pattern; this use is also known as the '' Kleene star'' or ''Kleene closure'' after Stephen Kleene.
* In Unified Modeling Language, the asterisk is used to denote zero to many classes.
* In some command line interfaces, such as the Unix shell and Microsoft
Microsoft Corporation is an American multinational corporation and technology company, technology conglomerate headquartered in Redmond, Washington. Founded in 1975, the company became influential in the History of personal computers#The ear ...
's CMD, the asterisk is the '' wildcard character'' (or wildcard symbol) and stands for any string of characters. A common use of the wildcard is in searching for files on a computer. For instance, if a user wished to find a document called Document 1
, search terms such as Doc*
and D*ment*
would return this file. Due to being a wildcard, they could also return files like Document 2
and (only the latter) Dark Knight Monument.jpg
. Document*
would in fact return any file that begins with Document
, and D*ment*
any file that began with D and had 'ment' somewhere in its name.
* In some graphical user interface
A graphical user interface, or GUI, is a form of user interface that allows user (computing), users to human–computer interaction, interact with electronic devices through Graphics, graphical icon (computing), icons and visual indicators such ...
s, an asterisk is pre- or affixed to the current working document name shown in a window's title bar to indicate that unsaved changes exist.
* In many computing and Internet
The Internet (or internet) is the Global network, global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a internetworking, network of networks ...
applications, an asterisk is displayed in place of the characters of sensitive or confidential visible information, such as a password.
* In Commodore (and related) file systems, an asterisk appearing next to a filename in a directory listing denotes an improperly closed file, commonly called a "splat file".
* In travel industry Global Distribution Systems, the asterisk is the display command to retrieve all or part of a Passenger Name Record.
* In HTML
Hypertext Markup Language (HTML) is the standard markup language for documents designed to be displayed in a web browser. It defines the content and structure of web content. It is often assisted by technologies such as Cascading Style Sheets ( ...
web forms, a (usually red) asterisk can be used to denote required fields.
* Chat room etiquette calls on one asterisk to correct a misspelled word or typo that has already been submitted. For example, one could post lck
, then follow it with *luck
or luck*
(the placement of the * on the left or right is a matter of personal style) to correct the word's spelling, or if it's someone else that notices the mistake, they might also use *luck
or luck*
. This also applies to typos that result in a different word from the intended one but are correctly spelled.
** Enclosing a phrase between two asterisks is used to denote an action the user is "performing", e.g. *pulls out a paper*
, although this usage is also common on forums, and less so on most chat rooms due to /me
or similar commands. Hyphen
The hyphen is a punctuation mark used to join words and to separate syllables of a single word. The use of hyphens is called hyphenation.
The hyphen is sometimes confused with dashes (en dash , em dash and others), which are wider, or with t ...
s (-action-
) and double colons (::action::
) as well as the operator /me
are also used for similar purposes.
* In Markdown and other markup languages, surrounding a set of characters or words in one asterisk italicizes, two asterisks bolds, and three asterisks both italicizes and bolds. See the table below for examples of all three uses of the asterisk in Markdown, including how it translates to HTML and how it renders.
Adding machines and printing calculators
* Some models of adding machines and printing calculators use the asterisk to denote the ''total'', or the terminal sum or difference of an addition or subtraction sequence, respectively. The symbol is sometimes given on the printout to indicate this total.
Programming languages
Many programming language
A programming language is a system of notation for writing computer programs.
Programming languages are described in terms of their Syntax (programming languages), syntax (form) and semantics (computer science), semantics (meaning), usually def ...
s and calculators use the asterisk as a symbol for multiplication
Multiplication is one of the four elementary mathematical operations of arithmetic, with the other ones being addition, subtraction, and division (mathematics), division. The result of a multiplication operation is called a ''Product (mathem ...
. It also has a number of special meanings in specific languages, for instance:
* In some languages such as C, C++, and Go, the asterisk is used to dereference or declare a pointer variable.
* In Common Lisp, the names of global variables are conventionally set off with asterisks, *LIKE-THIS*
.
* In Ada, Fortran, Perl, Python, Ruby, some dialects of Pascal, and many others, a double asterisk is used to signify exponentiation
In mathematics, exponentiation, denoted , is an operation (mathematics), operation involving two numbers: the ''base'', , and the ''exponent'' or ''power'', . When is a positive integer, exponentiation corresponds to repeated multiplication ...
: 5**3
is 53 = 125.
* In Perl, the asterisk is used to refer to the '' typeglob'' of all variables with a given name.
* In Ruby and Python, the asterisk has two specific uses. First, the unary * operator applied to a list object inside a function call will expand that list into the positional arguments of the function call. Second, a parameter preceded by * in the parameter list in a function definition will result in any extra positional parameters being aggregated into a tuple (Python) or array (Ruby), and likewise a parameter preceded by ** will result in any extra keyword parameters being aggregated into a dictionary
A dictionary is a listing of lexemes from the lexicon of one or more specific languages, often arranged Alphabetical order, alphabetically (or by Semitic root, consonantal root for Semitic languages or radical-and-stroke sorting, radical an ...
(Python) or hash (Ruby):
def function1(a, b, c, d):
print(a, b, c, d)
def function2(first, *args):
# args will be a tuple
# the name 'args' is convention: it may be any parameter name
print(args)
def function3(first, **kwargs):
# kwargs will be a dict
# the name 'kwargs' is convention: it may be any parameter name
print(kwargs)
function1(1, 2, 3, 4) # prints 1 2 3 4
function1(* , 2, 3, 4 # prints 1 2 3 4
function1(**) # prints 5 6 7 8
function2(1, 2, 3, 4) # prints (2, 3, 4), 1 is not part of args
function2(99) # prints (), unfilled *parameter will be ()
function3(0, e=3, f=9) # prints , 0 is not part of kwargs
function3(0) # prints , unfilled **parameter will be
* In APL, the asterisk represents the exponential and exponentiation
In mathematics, exponentiation, denoted , is an operation (mathematics), operation involving two numbers: the ''base'', , and the ''exponent'' or ''power'', . When is a positive integer, exponentiation corresponds to repeated multiplication ...
functions, with *X
representing eX, and Y*X
representing YX.
* In IBM Job Control Language, the asterisk has various functions, including in-stream data in the DD statement, the default print stream as SYSOUT=*
, and as a self-reference in place of a procedure step name to refer to the same procedure step where it appears.
* In Haskell, the asterisk represents the set of well-formed, fully applied types; that is, a 0-ary ''kind'' of types.
=Comments in programming languages
=
In the B programming language and languages that borrow syntax from it, such as C, PHP, Java
Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...
, or C#, comments in the source code (for information to people, ignored by the compiler
In computing, a compiler is a computer program that Translator (computing), translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primaril ...
) are marked by an asterisk combined with the slash:
/* This section displays message if user input was not valid
(comment ignored by compiler) */
CSS also uses this comment format:
body
Some Pascal-like programming languages, such as Object Pascal, Modula-2, Modula-3, and Oberon, and other languages such as ML, Wolfram Language ( Mathematica), AppleScript, OCaml, Standard ML, and Maple, use an asterisk combined with a parenthesis:
(* Do not change this variable - it is used later
(comment ignored by compiler) *)
Each computing language has its own way of handling comments; and similar notations are not universal.
History of information technology
The asterisk was a supported symbol on the IBM 026 Keypunch (introduced in 1949 and used to create punch cards with data for early computer systems). It was also included in the FIELDATA character encoding and the ASCII
ASCII ( ), an acronym for American Standard Code for Information Interchange, is a character encoding standard for representing a particular set of 95 (English language focused) printable character, printable and 33 control character, control c ...
standard.
Economics
* In economics
Economics () is a behavioral science that studies the Production (economics), production, distribution (economics), distribution, and Consumption (economics), consumption of goods and services.
Economics focuses on the behaviour and interac ...
, the use of an asterisk superscript indicates that the variable such as price, output
Output may refer to:
* The information produced by a computer, see Input/output
* An output state of a system, see state (computer science)
* Output (economics), the amount of goods and services produced
** Gross output in economics, the valu ...
, or employment
Employment is a relationship between two party (law), parties Regulation, regulating the provision of paid Labour (human activity), labour services. Usually based on a employment contract, contract, one party, the employer, which might be a cor ...
is at its optimal level (that which is achieved in a perfect market situation). For instance, is the price level when output is at its corresponding optimal level of .
* Also in international economics asterisks are commonly used to denote economic variables in a foreign country. So, for example, is the price of the home good and is the price of the foreign good, etc.
Education
* In the A-Level examinations in the United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...
and the PSLE in Singapore
Singapore, officially the Republic of Singapore, is an island country and city-state in Southeast Asia. The country's territory comprises one main island, 63 satellite islands and islets, and one outlying islet. It is about one degree ...
, A* ("''A''-star") is a special top grade that is distinguished from grade A.
* In the Hong Kong Diploma of Secondary Education
The Hong Kong Diploma of Secondary Education Examination (HKDSEE) is an examination organised by the Hong Kong Examinations and Assessment Authority (HKEAA). The HKDSE examination is Hong Kong's university entrance examination, administer ...
(HKDSE) examination in Hong Kong
Hong Kong)., Legally Hong Kong, China in international treaties and organizations. is a special administrative region of China. With 7.5 million residents in a territory, Hong Kong is the fourth most densely populated region in the wor ...
, 5** (5-star-star) and 5* (5-star) are two special top grades that are distinguished from Level 5. Level 5** is the highest level a candidate can attain in HKDSE.
Fluid mechanics
In fluid mechanics an asterisk in superscript is sometimes used to mean a property at sonic speed.
Games
*Certain categories of character types in role-playing game
A role-playing game (sometimes spelled roleplaying game, or abbreviated as RPG) is a game in which players assume the roles of player character, characters in a fictional Setting (narrative), setting. Players take responsibility for acting out ...
s are called splats, and the game supplements describing them are called splatbooks. This usage originated with the shorthand "*book" for this type of supplement to various World of Darkness games, such as ''Clanbook: Ventrue'' (for '' Vampire: The Masquerade'') or ''Tribebook: Black Furies'' (for '' Werewolf: The Apocalypse''), and this usage has spread to other games with similar character-type supplements. For example, '' Dungeons & Dragons'' Third Edition has had several lines of splatbooks: the "X & Y" series including ''Sword & Fist'' and ''Tome & Blood'' prior to the "3.5" revision, the "Complete X" series including ''Complete Warrior'' and ''Complete Divine'', and the "Races of X" series including ''Races of Stone'' and ''Races of the Wild''.
*In Magic: The Gathering, an asterisk is used on a creature's power and/or toughness when it's a variable amount.
*In many MUDs and MOOs, as well as "male", "female", and other more esoteric genders, there is a gender called "splat", which uses an asterisk to replace the letters that differ in standard English gender pronouns. For example, ''h*'' is used rather than ''him'' or ''her''. Also, asterisks are used to signify doing an action, for example, "*''action''*".
*Game show
A game show (or gameshow) is a genre of broadcast viewing entertainment where contestants compete in a game for rewards. The shows are typically directed by a game show host, host, who explains the rules of the program as well as commentating a ...
producer Mark Goodson used a six-pointed asterisk as his trademark. It is featured prominently on many set pieces from '' The Price Is Right.''
*Scrabble
''Scrabble'' is a word game in which two to four players score points by placing tiles, each bearing a single letter, onto a Board game, game board divided into a 15×15 grid of squares. The tiles must form words that, in crossword fashion, re ...
players put an asterisk after a word to indicate that an illegal play was made.
Human genetics
*In human genetics, * is used to denote that someone is a member of a haplogroup and not any of its subclades (see * (haplogroup)).
Linguistics
In linguistics
Linguistics is the scientific study of language. The areas of linguistic analysis are syntax (rules governing the structure of sentences), semantics (meaning), Morphology (linguistics), morphology (structure of words), phonetics (speech sounds ...
, an asterisk may be used for a range of purposes depending on what is being discussed. The symbol is used to indicate reconstructed words of proto-languages
In the tree model of historical linguistics, a proto-language is a postulated ancestral language from which a number of attested languages are believed to have descended by evolution, forming a language family. Proto-languages are usually unattest ...
(for which there are no records). For modern languages, it may be placed before posited problematic word forms, phrases or sentences to flag that they are hypothetical, ungrammatical, unpronounceable, etc.
Historical linguist August Schleicher is cited as first using the asterisk for linguistic purposes, specifically for unattested forms that are linguistic reconstructions.
Using the asterisk for descriptive and not just historical purposes arose in the 20th century. By analogy with its use in historical linguistics, the asterisk was variously prepended to "hypothetical" or "unattested" elements in modern language. Its usage also expanded to include "non-existent" or "impossible" forms. Leonard Bloomfield (1933) uses the asterisk with forms such as ''*cran,'' impossible to occur in isolation: ''cran-'' only occurs within the compound ''cranberry''. Such usage for a "non-existent form" was also found in French, German and Italian works in the middle of the 20th century.
Asterisk usage in linguistics later came to include not just impossible forms, but " ungrammatical sentences", those that are "ill formed for the native speaker". The expansion of asterisk usage to entire sentences is often credited to Noam Chomsky, but Chomsky in 1968 already describes this usage as "conventional". Linguist Fred Householder claims some credit, but Giorgio Graffi argues that using an asterisk for this purpose predates his works.
The meaning of the asterisk usage in specific linguistic works may go unelucidated so can be unclear. Linguistics sometimes uses double asterisks (), another symbol such as the question mark, or both symbols (e.g. ) to indicate degrees of unacceptability.
Historical linguistics
In historical linguistics
Historical linguistics, also known as diachronic linguistics, is the scientific study of how languages change over time. It seeks to understand the nature and causes of linguistic change and to trace the evolution of languages. Historical li ...
, the asterisk marks words or phrases that are not directly recorded in texts or other media, and that are therefore reconstructed on the basis of other linguistic material by the comparative method.
In the following example, the Proto-Germanic
Proto-Germanic (abbreviated PGmc; also called Common Germanic) is the linguistic reconstruction, reconstructed proto-language of the Germanic languages, Germanic branch of the Indo-European languages.
Proto-Germanic eventually developed from ...
word is a reconstructed form.
* → → ''eleven''
A double asterisk () sometimes indicates an intermediary or proximate reconstructed form (e.g. a single asterisk for reconstructed thirteenth century Chinese and a double asterisk for reconstructions of older Ancient Chinese or a double asterisk for proto- Popolocan and a single asterisk for intermediary forms).
In other cases, the double asterisk denotes a form that would be expected according to a rule, but is not actually found. That is, it indicates a reconstructed form that is not found or used, and in place of which ''another'' form is found in actual usage:
* For the plural, * would be expected, but separate masculine plural and feminine plural are found as irregular forms.
Ungrammaticality
In most areas of linguistics, but especially in syntax, an asterisk in front of a word or phrase indicates that the word or phrase is not used because it is ungrammatical.
*wake her up / *wake up her
An asterisk before a parenthesis indicates that the lack of the word or phrase inside is ungrammatical, while an asterisk after the opening bracket of the parenthesis indicates that the existence of the word or phrase inside is ungrammatical—e.g., the following indicates "go the station" would be ungrammatical:
*go *(to) the station
Use of an asterisk to denote forms or sentences that are ungrammatical is often complemented by the use of the question mark () to indicate a word, phrase or sentence that is avoided, questionable or strange, but not necessarily outright ungrammatical.
Other sources go further and use several symbols (e.g. the asterisk, question mark, and degree symbol
The degree symbol or degree sign, , is a glyph or symbol that is used, among other things, to represent degrees of arc (e.g. in geographic coordinate systems), hours (in the medical field), degrees of temperature or alcohol proof. The symbo ...
) to indicate gradations or a continuum of acceptability.
= Ambiguity
=
Since a word marked with an asterisk could mean either "unattested" or "impossible", it is important in some contexts to distinguish these meanings. In general, authors retain asterisks for "unattested", and prefix , , , or for the latter meaning. An alternative is to append the asterisk (or another symbol, possibly to differentiate between even more cases) at the end.
Optimality theory
In optimality theory, asterisks are used as "violation marks" in tableau cells to denote a violation of a constraint by an output form.
Phonetic transcription
In phonetic transcription using the International Phonetic Alphabet
The International Phonetic Alphabet (IPA) is an alphabetic system of phonetic notation based primarily on the Latin script. It was devised by the International Phonetic Association in the late 19th century as a standard written representation ...
and similar systems, an asterisk was historically used to denote that the word it preceded was a proper noun. See this example from W. Perrett's 1921 transcription of Gottfried Keller's :
:, ! .
:(')
This convention is no longer usual.
Mathematics
The asterisk has many uses in mathematics
Mathematics is a field of study that discovers and organizes methods, Mathematical theory, theories and theorems that are developed and Mathematical proof, proved for the needs of empirical sciences and mathematics itself. There are many ar ...
. The following list highlights some common uses and is not exhaustive.
;stand-alone:
* An arbitrary point in some set. Seen, for example, when computing Riemann sums or when contracting a simply connected group to the singleton set .
;as a unary operator, denoted in prefix notation:
* The Hodge star operator
In mathematics, the Hodge star operator or Hodge star is a linear map defined on the exterior algebra of a Dimension (vector space), finite-dimensional orientation (vector space), oriented vector space endowed with a Degenerate bilinear form, nonde ...
on vector spaces .
;as a unary operator, written as a subscript:
* The pushforward (differential) of a smooth map between two smooth manifolds, denoted .
* And more generally the application of any covariant functor
In mathematics, specifically category theory, a functor is a Map (mathematics), mapping between Category (mathematics), categories. Functors were first considered in algebraic topology, where algebraic objects (such as the fundamental group) ar ...
, where no doubt exists over which functor is meant.
;as a unary operator, written as a superscript:
* The complex conjugate of a complex number (the more common notation is ).
* The conjugate in a composition algebra
* The conjugate transpose, Hermitian transpose, or adjoint matrix of a matrix.
* Hermitian adjoint
In mathematics, specifically in operator theory, each linear operator A on an inner product space defines a Hermitian adjoint (or adjoint) operator A^* on that space according to the rule
:\langle Ax,y \rangle = \langle x,A^*y \rangle,
where \l ...
.
* The multiplicative group of the units of a ring; when the ring is a field, this is the group of all nonzero elements. For example,
* The dual space of a vector space , denoted .
* The combination of an indexed collection of objects into one example, e.g. the combination of all the cohomology groups into the cohomology ring .
* The reflexive transitive closure of a binary relation.
* In statistics, and are given critical points for -distributions and -distributions, respectively.
;as a binary operator, in infix notation:
* A notation for an arbitrary binary operator.
* The free product of two groups.
* is a convolution of with .
* A notation for the horizontal composition of two natural transformations.
* A notation to denote a parallel sum of two operands (most authors, however, instead use a or sign for this purpose).
The asterisk is used in all branches of mathematics to designate a correspondence between two quantities denoted by the same letter – one with the asterisk and one without.
Mathematical typography
In fine mathematical typography, the Unicode
Unicode or ''The Unicode Standard'' or TUS is a character encoding standard maintained by the Unicode Consortium designed to support the use of text in all of the world's writing systems that can be digitized. Version 16.0 defines 154,998 Char ...
character (in HTML, ∗; not to be confused with ) 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 for a large asterisk that lines up with the other mathematical operators, sitting on the math centerline rather than on the text baseline.
Music
* In musical notation the sign () indicates when the sustain pedal of the piano should be lifted.
* In liturgical music, an asterisk is often used to denote a deliberate pause.
Religious texts
*In the Geneva Bible and the King James Bible, an asterisk is used to indicate a marginal comment or scripture reference.
*In the Leeser Bible, an asterisk is used to mark off the seven subdivisions of the weekly Torah portion. It is also used to mark the few verses to be repeated by the reader of the Haftara.
*In American printings of the '' Book of Common Prayer'', an asterisk is used to divide a verse of a Psalm in two portions for responsive reading. British printings use a spaced colon (" : ") for the same purpose.
*In pointed psalms, an asterisk is used to denote a break or breath.
Star of Life
A Star of Life, a six-bar asterisk overlaid with the Rod of Asclepius (the symbol of health), may be used as an alternative to cross or crescent symbols on ambulances.
Statistical results
In many scientific publications, the asterisk is employed as a shorthand to denote the statistical significance of results when testing hypotheses
A hypothesis (: hypotheses) is a proposed explanation for a phenomenon. A scientific method, scientific hypothesis must be based on observations and make a testable and reproducible prediction about reality, in a process beginning with an educ ...
. When the likelihood that a result occurred by chance alone is below a certain level, one or more asterisks are displayed. Popular significance levels are <0.05 (*), <0.01 (**), and <0.001 (***).
Telephony
On a tone dialling telephone keypad, the asterisk (called ''star'') is one of the two special keys (the other is the 'square key almost invariably replaced by the number sign
The symbol is known as the number sign, hash, (or in North America) the pound sign. The symbol has historically been used for a wide range of purposes including the designation of an ordinal number and as a Typographic ligature, ligatured abbre ...
(called 'pound sign' (US), 'hash' (other countries), or 'hex'), and is found to the left of the zero). They are used to navigate menus in systems such as voice mail
A voicemail system (also known as voice message or voice bank) is a computer-based system that allows callers to leave a Voice recording, recorded message when the recipient has been unable (or unwilling) to answer the Telephone, phone. Calls may ...
, or in vertical service codes. Its codepoint in Unicode
Unicode or ''The Unicode Standard'' or TUS is a character encoding standard maintained by the Unicode Consortium designed to support the use of text in all of the world's writing systems that can be digitized. Version 16.0 defines 154,998 Char ...
is as a valid alternative usage.
Typography
* The asterisk is used to call out a footnote, especially when there is only one on the page. Less commonly, multiple asterisks are used to denote different footnotes on a page (i.e., *, **, ***).[Walter Thomas Rogers: ''A Manual of Bibliography: Being an Introduction to the Knowledge of Books, Library Management and the Art of Cataloguing, with a List of Bibliographical Works of Reference, a Latin-English and English-Latin Topographical Index of Ancient Printing Centres, and a Glossary.'' H. Grevel & Co., London 1891, p. 184]
Google Books
). Typically, an asterisk is positioned after a word or phrase and preceding its accompanying footnote. Other characters are also used for this purpose, such as dagger (†, ‡) or superscript letters and numbers (as in Wikipedia). In marketing and advertising, asterisks or other symbols are used to refer readers discreetly to terms or conditions for a certain statement, the " small print".
* In English-language typography the asterisk is placed after all other punctuation marks (for example, commas, colons, or periods) except for the dash.
* Three spaced asterisks centered on a page is called a dinkus and may represent a jump to a different scene, thought, or section.
* A group of three asterisks arranged in a triangular formation is called an asterism. It may be used instead of a name on a title page.
* One or more asterisks may be used as censorship over all or part of a word.
* Asterisks are sometimes used as an alternative to typographical bullets to indicate items of a list.
* Asterisks can be used in textual media to represent * emphasis* when bold or italic text is not available (e.g., Twitter, text messaging).
* Asterisks may denote conversational repair, or corrections to misspelling or misstatements in previous electronic messages, particularly when replacement or retraction of a previous writing is not possible, such as with "immediate delivery" messages or "instant messages" that can not be edited. Usually this takes the form of a message consisting solely of the corrected text, with an asterisk placed before (or after) the correction. For example, one might send a message reading "*morning" or "morning*" to correct the misspelling in the message "I had a good ".
* Bounding asterisks as "a kind of self-describing stage direction", as linguist Ben Zimmer has put it. For example, in "''Another gas station robbery *sigh*''", the writer uses *sigh* to express disappointment (but does not necessarily literally sigh).
* Bounding asterisks can also represent an action in online situations where they aren't shown.
Unique uses in other languages
German
Encodings
The Unicode
Unicode or ''The Unicode Standard'' or TUS is a character encoding standard maintained by the Unicode Consortium designed to support the use of text in all of the world's writing systems that can be digitized. Version 16.0 defines 154,998 Char ...
standard has a variety of asterisk-like characters, compared in the table below. (Characters will display differently in different browsers and fonts.) The reason there are so many is chiefly because of the controversial decision to include in Unicode the entire Zapf Dingbats symbol font.
In Unicode
*
* ͙
*
*
*
*
*
*
*
* May be used as the star key (telephony)
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
See also
*
*
*
*
* , for example to identify errors
* List of typographical symbols and punctuation marks
* Reference mark (), the symbol used in Chinese, Japanese and Korean typography for an equivalent purpose
* Sextile an asterisk-like astrological symbol (⚹), six lines radiating at 60⁰ intervals
Notes
References
{{navbox punctuation
Punctuation
Ancient Greek punctuation