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The comma is a
punctuation Punctuation (or sometimes interpunction) is the use of spacing, conventional signs (called punctuation marks), and certain typographical devices as aids to the understanding and correct reading of written text, whether read silently or aloud. An ...
mark that appears in several variants in different languages. It has the same shape as an
apostrophe The apostrophe ( or ) is a punctuation Punctuation (or sometimes interpunction) is the use of spacing, conventional signs (called punctuation marks), and certain typographical devices as aids to the understanding and correct reading of wri ...

apostrophe
or single closing
quotation mark Quotation marks, also known as quotes, quote marks, speech marks, inverted commas, or talking marks, are punctuation Punctuation (or sometimes interpunction) is the use of spacing, conventional signs (called punctuation marks), and cer ...
() in many
typeface A typeface is the design of lettering Lettering is an umbrella term In linguistics Linguistics is the science, scientific study of language. It encompasses the analysis of every aspect of language, as well as the methods for studying ...

typeface
s, but it differs from them in being placed on the baseline of the text. Some typefaces render it as a small line, slightly curved or straight but inclined from the vertical. Other fonts give it the appearance of a miniature filled-in figure on the baseline. The comma is used in many contexts and
language A language is a structured system of communication Communication (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the ...

language
s, mainly to separate parts of a
sentence Sentence(s) or The Sentence may refer to: Common uses * Sentence (law), the punishment a judge gives to a defendant found guilty of a crime * Sentence (linguistics), a grammatical unit of language * Sentence (mathematical logic), a formula not cont ...
such as
clause In language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be in relation with") is "an apparent answer to the painful divisions between self and other, private a ...
s and items in lists mainly when there are three or more items listed. The word ''comma'' comes from the
Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 million as of ...
(), which originally meant a cut-off piece, specifically in
grammar In linguistics Linguistics is the scientific study of language, meaning that it is a comprehensive, systematic, objective, and precise study of language. Linguistics encompasses the analysis of every aspect of language, as well as the ...
, a short
clause In language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be in relation with") is "an apparent answer to the painful divisions between self and other, private a ...
. A comma-shaped mark is used as a
diacritic A diacritic (also diacritical mark, diacritical point, diacritical sign, or accent) is a glyph The term glyph is used in typography File:metal movable type.jpg, 225px, Movable type being assembled on a composing stick using pieces that ...
in several writing systems and is considered distinct from the
cedilla A cedilla ( ; from Spanish Spanish may refer to: * Items from or related to Spain: **Spaniards, a nation and ethnic group indigenous to Spain **Spanish language **Spanish cuisine Other places * Spanish, Ontario, Canada * Spanish River (di ...

cedilla
. In
Ancient Greek Ancient Greek includes the forms of the Greek language Greek ( el, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally referred to by speakers simply as Greek (, ), refers collectively to the diale ...
, the rough and
smooth breathing The smooth breathing ( grc, ψιλὸν πνεῦμα, psilòn pneûma; ell, ψιλή ''psilí''; la, spīritus lēnis) is a diacritical mark A diacritic (also diacritical mark, diacritical point, diacritical sign, or accent) is a glyph ...
s () appear above the letter. In Latvian,
Romanian Romanian may refer to: *anything of, from, or related to the country and nation of Romania Romania ( ; ro, România ) is a country at the crossroads of Central Europe, Central, Eastern Europe, Eastern and Southeast Europe, Southeastern Euro ...
, and Livonian, the comma diacritic appears below the letter, as in . ''For the notation'' ''and'' /x/ ''used in this article, see
grapheme In linguistics Linguistics is the scientific study of language A language is a structured system of communication used by humans, including speech (spoken language), gestures (Signed language, sign language) and writing. Most langu ...

grapheme
and
phoneme In phonology and linguistics, a phoneme is a unit of sound that distinguishes one word from another in a particular language. For example, in most List of dialects of English, dialects of English, with the notable exception of the West Midlan ...
respectively.''


History

The development of
punctuation Punctuation (or sometimes interpunction) is the use of spacing, conventional signs (called punctuation marks), and certain typographical devices as aids to the understanding and correct reading of written text, whether read silently or aloud. An ...
is much more recent than the alphabet. In the 3rd century BC,
Aristophanes of Byzantium __NOTOC__ Aristophanes of Byzantium Byzantium () or Byzantion ( grc-gre, Βυζάντιον) was an ancient Greek Ancient Greek includes the forms of the used in and the from around 1500 BC to 300 BC. It is often roughly divide ...
invented a system of single
dots Dots or The Dots may refer to: *Dots (candy) Dots, or Mason Dots (trademarked DOTS), is a brand of gumdrop, gum drops marketed by Tootsie Roll Industries, which claims that "since its 1945 launch," the candy has become "America's...#1 selling gum ...

dots
() at varying levels, which separated verses and indicated the amount of breath needed to complete each fragment of the text when
reading Reading is the process of taking in the sense or meaning of letters, symbols, ''etc.'', especially by sight or touch. For educators and researchers, reading is a multifaceted process involving such areas as word recognition, orthography An ...
aloud. The different lengths were signified by a dot at the bottom, middle, or top of the line. For a short passage, a in the form of a dot was placed mid-level. This is the origin of the concept of a comma, although the name came to be used for the mark itself instead of the clause it separated. The mark used today is descended from a , a diagonal
slash Slash may refer to: * Slash (punctuation), the "/" character Arts and entertainment Fictional characters * Slash (Marvel Comics) * Slash (Teenage Mutant Ninja Turtles), Slash (''Teenage Mutant Ninja Turtles'') Music * Slash (musician), stage n ...
known as , used from the 13th to 17th centuries to represent a pause. The modern comma was first used by
Aldus Manutius Aldus Pius Manutius (; it, Aldo Pio Manuzio; 1449/14526 February 1515) was an Italian humanist Humanism is a philosophical Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, ...

Aldus Manutius
.


Uses in English

In general, the comma shows that the words immediately before the comma are less closely or exclusively linked
grammatically In linguistics Linguistics is the science, scientific study of language. It encompasses the analysis of every aspect of language, as well as the methods for studying and modeling them. The traditional areas of linguistic analysis includ ...
to those immediately after the comma than they might be otherwise. The comma performs a number of functions in
English English usually refers to: * English language English is a West Germanic languages, West Germanic language first spoken in History of Anglo-Saxon England, early medieval England, which has eventually become the World language, leading lan ...

English
writing. It is used in generally similar ways in other languages, particularly European ones, although the rules on comma usage – and their rigidity – vary from language to language.


The serial comma

Commas are placed between items in lists, as in ''They own a cat, a dog, two rabbits, and seven mice.'' Whether the final conjunction, most frequently ''and'', should be preceded by a comma, called the ''serial comma'', is one of the most disputed linguistic or stylistic questions in English. *They served apples, peaches, and bananas. (serial comma used) *We cleaned up cores, pits and skins. (serial comma omitted) The serial comma is used much more often, usually routinely, in the United States. A majority of American style guides mandate its use, including ''
The Chicago Manual of Style ''The Chicago Manual of Style'' (abbreviated in writing as ''CMOS'' or ''CMS'', or sometimes as ''Chicago'') is a style guide for American English published since 1906 by the University of Chicago Press. Its 17 editions have prescribed writi ...
'', Strunk and
White White is the lightest color Color (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the Unite ...
's classic ''
The Elements of Style ''The Elements of Style'' is an American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currentl ...
'', and the ''
U.S. Government Printing Office
U.S. Government Printing Office
Style Manual''. Conversely, the ''AP Stylebook'' for journalistic writing advises against it. The serial comma is also known as the Oxford comma, Harvard comma, or series comma. Although less common in British English, its usage occurs within both American and British English. It is called the Oxford comma because of its long history of use by Oxford University Press. According to ''New Hart's Rules'', "house style will dictate" whether to use the serial comma. "The general rule is that one style or the other should be used consistently." No association with region or dialect is suggested, other than that its use has been strongly advocated by Oxford University Press. Its use is preferred by Fowler's ''
Modern English Usage ''A Dictionary of Modern English Usage'' (1926), by Henry Watson Fowler Henry Watson Fowler (10 March 1858 – 26 December 1933) was an English schoolmaster, List of lexicographers, lexicographer and commentator on the usage of the English ...
''. It is recommended by the United States
Government Printing Office A government is the system or group of people governing an organized community, generally a State (polity), state. In the case of its broad associative definition, government normally consists of legislature, executive, and judiciary. ...
,
Harvard University Press Harvard University Press (HUP) is a publishing house Publishing is the activity of making information, literature, music, software and other content available to the public for sale or for free. Traditionally, the term refers to the distrib ...
, and the classic ''Elements of Style'' of
Strunk and White ''The Elements of Style'' is an American English writing style guide in numerous editions. The original was composed by William Strunk Jr. in 1918, and published by Harcourt (publisher), Harcourt in 1920, comprising eight "elementary rules of usag ...
. Use of a comma may prevent ambiguity: * The sentence ''I spoke to the boys, Sam and Tom'' could mean either ''I spoke to the boys and Sam and Tom'' (I spoke to more than three people) or ''I spoke to the boys, who are Sam and Tom'' (I spoke to two people); * ''I spoke to the boys, Sam, and Tom'' – must be ''the boys and Sam and Tom'' (I spoke to more than three people). The serial comma does not eliminate all confusion. Consider the following sentence: *''I thank my mother, Anne Smith, and Thomas.'' This could mean either ''my mother and Anne Smith and Thomas'' (three people) or ''my mother, who is Anne Smith; and Thomas'' (two people). This sentence might be recast as "my mother (Anne Smith) and Thomas" for clarity. * ''I thank my mother, Anne Smith and Thomas.'' Because the comma after "mother" is conventionally used to prepare the reader for an apposite phrase – that is, a renaming of or further information about a noun – this construction suggests that my mother's name is "Anne Smith and Thomas". Compare "I thank my friend, Smith and Wesson", in which the ambiguity is obvious to those who recognise Smith and Wesson as a business name. As a
rule of thumb ''Rule of thumb'' is an approximate method for doing something, based on practical experience rather than theory. This usage of the phrase can be traced back to the seventeenth century and has been associated with various trades where quantities w ...
, ''
The Guardian ''The Guardian'' is a British daily newspaper. It was founded in 1821 as ''The Manchester Guardian'', and changed its name in 1959. Along with its sister papers ''The Observer ''The Observer'' is a British newspaper published on Sun ...

The Guardian
Style Guide'' suggests that straightforward lists (''he ate ham, eggs and chips'') do not need a comma before the final "and", but sometimes it can help the reader (''he ate cereal, kippers, bacon, eggs, toast and marmalade, and tea''). ''The Chicago Manual of Style'' and other academic writing guides require the serial comma: all lists must have a comma before the "and" prefacing the last item in a series . If the individual items of a list are long, complex, affixed with description, or themselves contain commas,
semicolon The semicolon or semi-colon is a symbol commonly used as orthographic punctuation Punctuation (or sometimes interpunction) is the use of spacing, conventional signs (called punctuation marks), and certain typographical devices as aids to ...

semicolon
s may be preferred as separators, and the list may be introduced with a
colon Colon commonly refers to: * Colon (punctuation) (:), a punctuation mark * Major part of large intestine, the final section of the digestive system Colon may also refer to: Places * Colon, Michigan, US * Colon, Nebraska, US * Kowloon, Hong Kong, s ...

colon
. In
news headlines
news headlines
, a comma might replace the word "and", even if there are only two items, in order to save space, as in this headline from Reuters: * ''Trump, Macron engage in a little handshake diplomacy.''


Separation of clauses

Commas are often used to separate
clause In language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be in relation with") is "an apparent answer to the painful divisions between self and other, private a ...
s. In English, a comma is used to separate a
dependent clause A subordinate clause, dependent clause or embedded clause is a clause In language A language is a structured system of communication used by humans, including speech (spoken language), gestures (Signed language, sign language) and writing. M ...
from the
independent clause An independent clause (or main clause) is a clause In language, a clause is a part of the sentence that constitutes or comprises a predicate (grammar), predicate. A typical clause consists of a subject (grammar), subject and a predicate, the la ...
, if the dependent clause comes first: ''After I fed the cat, I brushed my clothes.'' (Compare this with ''I brushed my clothes after I fed the cat.'') A
relative clause A relative clause is typically a clause that modifies a noun A noun () is a word that functions as the name of a specific object or set of objects, such as living creatures, places, actions, qualities, states of existence, or ideas.Example nouns ...
takes commas if it is non-
restrictive In semantics Semantics (from grc, wikt:σημαντικός, σημαντικός ''sēmantikós'', "significant") is the study of meaning, reference, or truth. The term can be used to refer to subfields of several distinct disciplines, includ ...
, as in ''I cut down all the trees, which were over six feet tall.'' (Without the comma, this would mean that only the trees more than six feet tall were cut down.) Some style guides prescribe that two
independent clause An independent clause (or main clause) is a clause In language, a clause is a part of the sentence that constitutes or comprises a predicate (grammar), predicate. A typical clause consists of a subject (grammar), subject and a predicate, the la ...
s joined by a coordinating
conjunction Conjunction may refer to: * Conjunction (astronomy), in which two astronomical bodies appear close together in the sky * Conjunction (astrology), astrological aspect in horoscopic astrology * Conjunction (grammar), a part of speech * Logical conjun ...
(''for'', ''and'', ''nor'', ''but'', ''or'', ''yet'', ''so'') must be separated by a comma placed before the conjunction. In the following sentences, where the second clause is independent (because it can stand alone as a sentence), the comma is considered by those guides to be necessary: * ''Mary walked to the party, but she was unable to walk home.'' * ''Designer clothes are silly, and I can't afford them anyway.'' * ''Don't push that button, or twelve tons of high explosives will go off right under our feet!'' In the following sentences, where the second half of the sentence is not an independent clause (because it does not contain an explicit subject), those guides prescribe that the comma be omitted: * ''Mary walked to the party but was unable to walk home.'' * ''I think designer clothes are silly and can't afford them anyway.'' However, such guides permit the comma to be omitted if the second independent clause is very short, typically when the second independent clause is an
imperative Imperative may refer to: *Imperative mood, a grammatical mood (or mode) expressing commands, direct requests, and prohibitions *Imperative programming, a programming paradigm in computer science *Imperative logic *Imperative (film), ''Imperative'' ...
, as in: * ''Sit down and shut up.'' The above guidance is not universally accepted or applied. Long
coordinate clause In grammar In linguistics Linguistics is the scientific study of language, meaning that it is a comprehensive, systematic, objective, and precise study of language. Linguistics encompasses the analysis of every aspect of language, a ...
s are nonetheless usually separated by commas: * ''She had very little to live on, but she would never have dreamed of taking what was not hers.'' A comma between clauses may change the connotation, reducing or eliminating
ambiguity Ambiguity is a type of meaning Meaning most commonly refers to: * Meaning (linguistics), meaning which is communicated through the use of language * Meaning (philosophy), definition, elements, and types of meaning discussed in philosophy * ...
. In the following examples, the thing in the first sentence that is relaxing is the cool day, whereas in the second sentence it is the walk, since the introduction of commas makes "on a cool day" parenthetical: :''They took a walk on a cool day that was relaxing.'' :''They took a walk, on a cool day, that was relaxing.'' As more clauses are introduced, ambiguity accumulates, but when commas separate each clause, the clauses clearly become modifiers of just one thing. In the second sentence below, that thing is the walk: :''They took a walk in the park on a cool day that was relaxing.'' :''They took a walk, in the park, on a cool day, that was relaxing.'' In some languages, such as
German German(s) may refer to: Common uses * of or related to Germany * Germans, Germanic ethnic group, citizens of Germany or people of German ancestry * For citizens of Germany, see also German nationality law * German language The German la ...

German
and
Polish Polish may refer to: * Anything from or related to Poland Poland ( pl, Polska ), officially the Republic of Poland ( pl, Rzeczpospolita Polska, links=no ), is a country located in Central Europe. It is divided into 16 Voivodeships of Pol ...
, stricter rules apply on comma usage between clauses, with dependent clauses always being set off with commas, and commas being generally proscribed before certain coordinating conjunctions. The joining of two independent sentences with a comma and no conjunction (as in "It is nearly half past five, we cannot reach town before dark.") is known as a
comma splice In written English usage, a comma splice or comma fault is the use of a comma The comma is a punctuation Punctuation (or sometimes interpunction) is the use of spacing, conventional signs (called punctuation marks), and certain typographic ...
and is sometimes considered an error in English; in most cases a semicolon should be used instead. A comma splice should not be confused, though, with
asyndeton Asyndeton (, ; from the el, ἀσύνδετον, "unconnected", sometimes called asyndetism) is a literary scheme in which one or several conjunctions are deliberately omitted from a series of related clauses. Examples include ''veni, vidi, vici ...
, a literary device used for a specific effect in which coordinating conjunctions are purposely omitted.


Certain adverbs

Commas are always used to set off certain
adverb An adverb is a word or an expression that modifies a verb A verb () is a word (part of speech) that in syntax conveys an action (''bring'', ''read'', ''walk'', ''run'', ''learn''), an occurrence (''happen'', ''become''), or a state of being ...

adverb
s at the beginning of a sentence, including ''however'', ''in fact'', ''therefore'', ''nevertheless'', ''moreover'', ''furthermore'', and ''still''. * ''Therefore, a comma would be appropriate in this sentence.'' * ''Nevertheless, I will not use one.'' If these adverbs appear in the middle of a sentence, they are followed and preceded by a comma. As in the second of the two examples below, if a semicolon separates the two sentences and the second sentence starts with an adverb, this adverb is preceded by a semicolon and followed by a comma. * ''In this sentence, furthermore, commas would also be called for.'' * ''This sentence is similar; however, a semicolon is necessary as well.'' Using commas to offset certain adverbs is optional, including ''then'', ''so'', ''yet'', ''instead'', and ''too'' (meaning ''also''). * ''So, that's it for this rule.'' or * ''So that's it for this rule.'' * ''A comma would be appropriate in this sentence, too.'' or * ''A comma would be appropriate in this sentence too.''


Parenthetical phrases

Commas are often used to enclose
parenthetical A bracket is either of two tall fore- or back-facing punctuation Punctuation (or sometimes interpunction) is the use of spacing, conventional signs (called punctuation marks), and certain typographical devices as aids to the understanding ...
words and phrases within a sentence (i.e., information that is not essential to the meaning of the sentence). Such phrases are both preceded and followed by a comma, unless that would result in a doubling of punctuation marks or the parenthetical is at the start or end of the sentence. The following are examples of types of parenthetical phrases: *Introductory phrase: ''Once upon a time, my father ate a muffin.'' *Interjection: ''My father ate the muffin, gosh darn it!'' *Aside: ''My father, if you don't mind me telling you this, ate the muffin.'' *
Appositive Apposition is a grammatical construction in which two elements, normally noun phrasesA noun phrase, or nominal (phrase), is a phrase In everyday speech, a phrase is any group of words, often carrying a special idiomatic meaning; in this sense it ...
: ''My father, a jaded and bitter man, ate the muffin.'' *Absolute phrase: ''My father, his eyes flashing with rage, ate the muffin.'' *Free modifier: ''My father, chewing with unbridled fury, ate the muffin.'' *Resumptive modifier: ''My father ate the muffin, a muffin which no man had yet chewed.'' *Summative modifier: ''My father ate the muffin, a feat which no man had attempted.''


Between adjectives

A comma is used to separate ''coordinate adjectives'' (i.e.,
adjectives In linguistics Linguistics is the scientific study of language A language is a structured system of communication Communication (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Itali ...

adjectives
that directly and equally modify the following noun). Adjectives are considered coordinate if the meaning would be the same if their order were reversed or if ''and'' were placed between them. For example: *''The dull, incessant droning'' but ''the cute little cottage.'' *''The devious lazy red frog'' suggests there are lazy red frogs (one of which is devious), while ''the devious, lazy red frog'' does not carry this connotation.


Before quotations

Some writers precede quoted material that is the grammatical object of an active verb of speaking or writing with a comma, as in ''Mr. Kershner says, "You should know how to use a comma."'' Quotations that follow and support an assertion are often preceded by a
colon Colon commonly refers to: * Colon (punctuation) (:), a punctuation mark * Major part of large intestine, the final section of the digestive system Colon may also refer to: Places * Colon, Michigan, US * Colon, Nebraska, US * Kowloon, Hong Kong, s ...

colon
rather than a comma. Other writers do not put a comma before quotations unless one would occur anyway. Thus they would write ''Mr. Kershner says "You should know how to use a comma."''


In dates


Month day, year

When a date is written as a month followed by a day followed by a year, a comma separates the day from the year: December 19, 1941. This style is common in American English. The comma is used to avoid confusing consecutive numbers: December 19 1941. Most style manuals, including ''
The Chicago Manual of Style ''The Chicago Manual of Style'' (abbreviated in writing as ''CMOS'' or ''CMS'', or sometimes as ''Chicago'') is a style guide for American English published since 1906 by the University of Chicago Press. Its 17 editions have prescribed writi ...
'' and the ''
AP Stylebook The ''AP Stylebook'', also known by its full name ''The Associated Press Stylebook and Briefing on Media Law'', is an American-English grammar style and usage guide created by American journalists working for or connected with the Associated Pres ...
'', also recommend that the year be treated as a parenthetical, requiring a second comma after it: ''"Feb. 14, 1987, was the target date."'' If just month and year are given, no commas are used: "Her daughter April may return in June 2009 for the reunion."


Day month year

When the day precedes the month, the month name separates the numeric day and year, so commas are not necessary to separate them: "The Raid on Alexandria was carried out on 19 December 1941."


In geographical names

Commas are used to separate parts of geographical references, such as city and state (''Dallas, Texas'') or city and country (''Kampala, Uganda''). Additionally, most style manuals, including ''
The Chicago Manual of Style ''The Chicago Manual of Style'' (abbreviated in writing as ''CMOS'' or ''CMS'', or sometimes as ''Chicago'') is a style guide for American English published since 1906 by the University of Chicago Press. Its 17 editions have prescribed writi ...
'' and the ''AP Stylebook'', recommend that the second element be treated as a parenthetical, requiring a second comma after: ''"The plane landed in Kampala, Uganda, that evening."'' The
United States Postal Service The United States Postal Service (USPS; also known as the Post Office, U.S. Mail, or Postal Service) is an independent agency A regulatory agency or regulatory authority, is a Public benefit corporation Public-benefit corporation is a te ...
and
Royal Mail Royal Mail Group plc is a British multinational mail, postal service and courier company, originally established in 1516 as a department of the English government. The company's subsidiary Royal Mail Group Limited operates the brands Royal Mail (le ...

Royal Mail
recommend leaving out punctuation when writing addresses on actual letters and packages, as the marks hinder
optical character recognition Optical character recognition or optical character reader (OCR) is the electronic Electronic may refer to: *Electronics Electronics comprises the physics, engineering, technology and applications that deal with the emission, flow and contro ...
.


In mathematics

Similar to the case in natural languages, commas are often used to delineate the boundary between multiple
mathematical object A mathematical object is an abstract concept arising in mathematics. In the usual language of mathematics, an ''object'' is anything that has been (or could be) formally defined, and with which one may do deductive reasoning and mathematical proofs ...
s in a list (e.g., (3, 5, 12)). Commas are also used to indicate the
comma derivative In mathematics Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity (number theory), mathematical structure, structure (algebra), space (geometry), and calculus, change (mathematical analysis, analysis). It ...
of a
tensor In mathematics Mathematics (from Greek: ) includes the study of such topics as numbers (arithmetic and number theory), formulas and related structures (algebra), shapes and spaces in which they are contained (geometry), and quantities a ...

tensor
.


In numbers

In representing large numbers, from the right side to the left, English texts usually use commas to separate each group of three digits in front of the decimal. This is almost always done for numbers of six or more digits, and often for four or five digits but not in front of the number itself. However, in much of Europe, Southern Africa and Latin America,
period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Period, a descriptor for a historical or period drama ...

period
s or spaces are used instead; the comma is used as a
decimal separator A decimal separator is a symbol used to separate the integer An integer (from the Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally spoken in the ar ...

decimal separator
, equivalent to the use in English of the
decimal point A decimal separator is a symbol used to separate the integer An integer (from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spok ...

decimal point
. In India, the groups are two digits, except for the rightmost group. In some styles, the comma may not be used for this purpose at all (e.g. in the SI writing style); a space may be used to separate groups of three digits instead.


In names

Commas are used when rewriting names to present the surname first, generally in instances of alphabetization by surname: ''Smith, John.'' They are also used before many titles that follow a name: ''John Smith, Ph.D.'' Similarly in lists that are presented with an inversion: ''...; socks, green: 3 pairs; socks, red: 2 pairs; tie, regimental: 1''.


Ellipsis

Commas may be used to indicate that a word, or a group of words, has been omitted, as in ''The cat was white; the dog, brown.'' (Here the comma replaces ''was''.)


Vocative

Commas are placed before, after, or around a noun or pronoun used independently in speaking to some person, place, or thing: *''I hope, John, that you will read this.''


Between the subject and predicate

In his 1785 essay ''An Essay on Punctuation'', Joseph Robertson advocated a comma between the subject and predicate of long sentences for clarity; however, this usage is regarded as an error in modern times. *''The good taste of the present age, has not allowed us to neglect the cultivation of the English language.'' *''Whoever is capable of forgetting a benefit, is an enemy to society.''


Differences between American and British usage in placement of commas and quotation marks

The comma and the
quotation mark Quotation marks, also known as quotes, quote marks, speech marks, inverted commas, or talking marks, are punctuation Punctuation (or sometimes interpunction) is the use of spacing, conventional signs (called punctuation marks), and cer ...
can be paired in several ways. In Great Britain and many other parts of the world, punctuation is usually placed within quotation marks only if it is part of what is being quoted or referred to: *My mother gave me the nickname "Bobby Bobby Bob Bob Boy", which really made me angry. In American English, the comma is commonly included inside a quotation mark: *My mother gave me the nickname "Bobby Bobby Bob Bob Boy," which really made me angry. During the
Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a global war A world war is "a war War is an intense armed conflict between states State may refer to: Arts, entertainment, and media Literatur ...
, the British carried the comma over into abbreviations. Specifically, "Special Operations, Executive" was written "S.O.,E.". Nowadays, even the
full stop The full stop (Commonwealth English The use of the English language English is a West Germanic languages, West Germanic language first spoken in History of Anglo-Saxon England, early medieval England, which has eventually become the ...

full stop
s are frequently discarded.


Languages other than English


Western European languages

Western European languages like German, French, Italian, Spanish, and Portuguese use the same comma as English with similar spacing, though usage may be somewhat different. For instance, in Standard German, subordinate clauses are always preceded by commas.


Comma variants

The basic comma is defined in Unicode as , and many variants by typography or language are also defined. Some languages use a completely different sort of character for the purpose of the comma. There are also a number of comma-like
diacritic A diacritic (also diacritical mark, diacritical point, diacritical sign, or accent) is a glyph The term glyph is used in typography File:metal movable type.jpg, 225px, Movable type being assembled on a composing stick using pieces that ...
s with "COMMA" in their Unicode names. These do not serve a
punctuation Punctuation (or sometimes interpunction) is the use of spacing, conventional signs (called punctuation marks), and certain typographical devices as aids to the understanding and correct reading of written text, whether read silently or aloud. An ...
function. A comma-like low quotation mark is also available (shown below; raised single quotation marks are not shown). Various other Unicode characters combine commas or comma-like figures with other characters, and are not shown here..


Languages other than Western European

Korean punctuation uses both commas and
interpunct An interpunct, , also known as an interpoint, middle dot, middot and centered dot or centred dot, is a punctuation mark consisting of a vertically centered dot used for interword separation in ancient Latin alphabet, Latin script. (Word-separati ...

interpunct
s for lists. In Unicode 5.2.0 "numbers with commas" ( through ) were added to the
Enclosed Alphanumeric Supplement Enclosed Alphanumeric Supplement is a Unicode block consisting Latin alphabet characters and Arabic numerals enclosed in circles, ovals or boxes, used for a variety of purposes. It is encoded in the range U+1F100–U+1F1FF in the Supplement ...
block for compatibility with the
ARIB STD B24 character set Volume 1 of the Association of Radio Industries and Businesses (ARIB) STD-B24 standard for Broadcast Markup Language specifies, amongst other details, a character encoding for use in Japanese-language broadcasting. It was introduced on . The lates ...
.
Hebrew script The Hebrew alphabet ( he, wikt:אלפבית, אָלֶף־בֵּית עִבְרִי, ), known variously by scholars as the Ktav Ashuri, Jewish script, square script and block script, is an abjad script used in the writing of the Hebrew language ...
is also written from right to left. However,
Hebrew punctuation Hebrew punctuation Punctuation (or sometimes interpunction) is the use of spacing, conventional signs (called punctuation marks), and certain typographical devices as aids to the understanding and correct reading of written text, whether read ...
includes only a regular comma ().
Dravidian languages Dravidian languages (or sometimes Dravidic languages) are a family of languages In human society, family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other r ...
such as
Tamil Tamil may refer to: * Tamils, an ethnic group native to India, Sri Lanka and some other parts of Asia **Sri Lankan Tamils, Tamil people native to Sri Lanka **Tamil Malaysians, Tamil people native to Malaysia * Tamil language, a Dravidian languages, ...

Tamil
,
Telugu Telugu may refer to: * Telugu language, a major Dravidian language of India *Telugu people, an ethno-linguistic group of India * Telugu script, used to write the Telugu language ** Telugu (Unicode block), a block of Telugu characters in Unicode ...
,
Kannada Kannada (; ಕನ್ನಡ, ; less commonly known as Kanarese) is a Dravidian language Dravidian languages (or sometimes Dravidic languages) are a family of languages In human society, family (from la, familia) is a group of peop ...

Kannada
, and
Malayalam Malayalam (; , ) is a Dravidian language Dravidian languages (or sometimes Dravidic languages) are a family of languages In human society, family (from la, familia) is a group of people related either by consanguinity (by recogni ...

Malayalam
also use the punctuation mark in similar usage to that of European languages with similar spacing. :ta:கால்புள்ளி (தமிழ் நடை)


Computing

In the common
character Character(s) may refer to: Arts, entertainment, and media Literature * ''Character'' (novel), a 1936 Dutch novel by Ferdinand Bordewijk * ''Characters'' (Theophrastus), a classical Greek set of character sketches attributed to Theophrastus M ...
encoding systems
Unicode Unicode, formally the Unicode Standard, is an information technology Technical standard, standard for the consistent character encoding, encoding, representation, and handling of Character (computing), text expressed in most of the world's wri ...

Unicode
and
ASCII ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding Character encoding is the process of assigning numbers to graphical Graphics (from Greek Greek may refer to: Greece Anything of, ...
, character 44 ( 0x2C) corresponds to the comma symbol. The
HTML The HyperText Markup Language, or HTML is the standard markup language #REDIRECT Markup language In computer text processing, a markup language is a system for annotation, annotating a document in a way that is Syntax (logic), syntacticall ...

HTML
numeric character reference A numeric character reference (NCR) is a common markup construct used in SGML The Standard Generalized Markup Language (SGML; ISO The International Organization for Standardization (ISO ) is an international standard An international stand ...
is ,. In many computer languages commas are used as a field delimiter to separate arguments to a
function Function or functionality may refer to: Computing * Function key A function key is a key on a computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern comp ...
, to separate elements in a
list A ''list'' is any set of items. List or lists may also refer to: People * List (surname)List or Liste is a European surname. Notable people with the surname include: List * Friedrich List (1789–1846), German economist * Garrett List (194 ...
, and to perform data designation on multiple variables at once. In the
C programming language C (, as in the letter ''c'') is a general-purpose, procedural computer programming language A programming language is a formal language comprising a Instruction set architecture, set of instructions that produce various kinds of Input/outp ...
the comma symbol is an operator which evaluates its first
argument In logic Logic is an interdisciplinary field which studies truth and reasoning Reason is the capacity of consciously making sense of things, applying logic Logic (from Ancient Greek, Greek: grc, wikt:λογική, λογική, la ...
(which may have side-effects) and then returns the value of its evaluated second argument. This is useful in ''for''
statement Statement or statements may refer to: Common uses *Statement (computer science), the smallest standalone element of an imperative programming language *Statement (logic), declarative sentence that is either true or false *Statement, a Sentence_(lin ...
s and macros. In
Smalltalk Smalltalk is an object-oriented programming, object-oriented, dynamically typed reflection (computer science), reflective programming language. Smalltalk was created as the language underpinning the "new world" of computing exemplified by "human ...

Smalltalk
and APL, the
comma operator In the C and C++ C++ () is a general-purpose programming language In computer software, a general-purpose programming language is a programming language dedicated to a general-purpose, designed to be used for writing software in a wide var ...
is used to concatenate collections, including strings. In APL, it is also used monadically to rearrange the items of an array into a list. In
Prolog Prolog is a logic programming Logic programming is a programming paradigm which is largely based on formal logic. Any program written in a logic programming language is a set of sentences in logical form, expressing facts and rules about some ...

Prolog
, the comma is used to denote
Logical Conjunction In logic Logic is an interdisciplinary field which studies truth and reasoning. Informal logic seeks to characterize Validity (logic), valid arguments informally, for instance by listing varieties of fallacies. Formal logic represents st ...
("and"). The
comma-separated values A comma-separated values (CSV) file is a delimited text file that uses a comma The comma is a punctuation mark that appears in several variants in different languages. It has the same shape as an apostrophe The apostrophe ( or ) is ...
(CSV) format is very commonly used in exchanging text data between database and spreadsheet formats.


Diacritical usage

The comma is used as a
diacritic A diacritic (also diacritical mark, diacritical point, diacritical sign, or accent) is a glyph The term glyph is used in typography File:metal movable type.jpg, 225px, Movable type being assembled on a composing stick using pieces that ...
mark in
Romanian Romanian may refer to: *anything of, from, or related to the country and nation of Romania Romania ( ; ro, România ) is a country at the crossroads of Central Europe, Central, Eastern Europe, Eastern and Southeast Europe, Southeastern Euro ...
under (, ), and under (, ). A cedilla is occasionally used instead of it, but this is technically incorrect. The symbol ('') was used as part of the
Romanian transitional alphabet The Romanian transitional alphabet ( ro, Alfabetul român de tranziție), also known as the civil alphabet ( ro, alfabetul civil), was an alphabet used for the Re-latinization of Romanian, re-latinization of the Romanian language, Romanian literatur ...
(19th century) to indicate the sounds denoted by the Latin letter or letters , where derived from a Cyrillic ѕ (, ). The comma and the cedilla are both derivative of (a small cursive ) placed below the letter. From this standpoint alone, , , and could potentially be regarded as stand-ins for /sz/, /tz/, and /dz/ respectively. In Latvian, the comma is used on the letters , , , , and historically also , to indicate palatalization. Because the lowercase letter has a
descender In typography Typography is the art and technique of arranging type to make written language A written language is the representation of a spoken or gestural language A language is a structured system of communication used by ...

descender
, the comma is rotated 180° and placed over the letter. Although their
Adobe Adobe (; ) is a building material Building material is material used for construction. Many naturally occurring substances, such as clay, rocks, sand, and wood, even twigs and leaves, have been used to construct buildings. Apart from ...
glyph The term glyph is used in typography Typography is the art and technique of arranging type to make written language A written language is the representation of a spoken or gestural language A language is a structured system o ...
names are 'letter with comma', their names in the
Unicode Unicode, formally the Unicode Standard, is an information technology Technical standard, standard for the consistent character encoding, encoding, representation, and handling of Character (computing), text expressed in most of the world's wri ...

Unicode
Standard are 'letter with a cedilla'. They were introduced to the Unicode standard before 1992 and, per Unicode Consortium policy, their names cannot be altered. In Livonian, whose alphabet is based on a mixture of Latvian and
Estonian Estonian may refer to: *Something of, from, or related to Estonia, a country in the Baltic region in northern Europe *Estonians, people from Estonia, or of Estonian descent *Estonian language *Estonian cuisine *Estonian culture See also

* * La ...
alphabets, the comma is used on the letters , , , , to indicate palatalization in the same fashion as Latvian, except that Livonian uses and to represent the same
palatal The palate is the roof of the mouth in humans and other mammal Mammals (from Latin language, Latin , 'breast') are a group of vertebrate animals constituting the class (biology), class Mammalia (), and characterized by the presence of ma ...

palatal
plosive In phonetics Phonetics is a branch of linguistics Linguistics is the scientific study of language, meaning that it is a comprehensive, systematic, objective, and precise study of language. Linguistics encompasses the analysis of ev ...
phonemes which Latvian writes as and respectively. In
Czech Czech may refer to: * Anything from or related to the Czech Republic The Czech Republic, also known by its short-form name Czechia and formerly known as Bohemia, is a landlocked country A landlocked country is a country A countr ...
and
Slovak Slovak may refer to: * Something from, related to, or belonging to Slovakia (''Slovenská republika'') * Slovaks, a Western Slavic ethnic group * Slovak language, an Indo-European language that belongs to the West Slavic languages * Slovak, Arkans ...
, the diacritic in the characters , , and resembles a superscript comma, but it is used instead of a
caron A caron (), háček or haček ( or ; plural ''háčeks'' or ''háčky'') also known as a hachek, wedge, check, kvačica, strešica, mäkčeň, paukščiukas, inverted circumflex, inverted hat, or flying bird, is a diacritic A diacritic (al ...

caron
because the letter has an
ascenderAscender may refer to: *Ascender (climbing), a rope-climbing device *Ascender Corporation, a font company *Ascender (typography), a font feature *XP-55 Ascender, a prototype aircraft *Isuzu Ascender, a sports utility vehicle *JP Aerospace#Ascender, ...
. Other ascender letters with carons, such as letters (used in
Finnish Romani Finnish Kalo (''kaalengo tšimb'') is a language of the Romani language, Romani language family (a subgroup of Indo-European languages, Indo-European) spoken by Finnish Kale. The language is related to but not mutually intelligible with Scandoroman ...
and
LakotaLakota may refer to: * Lakota people, a confederation of seven related Native American tribes *Lakota language Lakota (), also referred to as Lakhota, Teton or Teton Sioux, is a Siouan language spoken by the Lakota people of the Sioux tribes. T ...
) and (used in
Skolt Sami Skolt Sami ( , "the Sámi language", or , "the Eastern Sámi language", if a distinction needs to be made between it and the other Sami languages) is a Uralic languages, Uralic, Sami languages, Sami language that is spoken by the Skolts, with a ...
), did not modify their carons to superscript commas. In 16th-century
Guatemala Guatemala ( ; ), officially the Republic of Guatemala ( es, República de Guatemala, links=no), is a country in Central America Central America ( es, América Central, , ''Centroamérica'' ) is a region of the Americas The Am ...

Guatemala
, the archaic letter
cuatrillo The cuatrillo with diacritic Cuatrillo (capital: Ꜭ, small: ꜭ) (Spanish language, Spanish for "little four") is a letter of several colonial Mayan alphabets in the Latin script that is based on the digit 4 (number), 4. It was invented by a Franc ...

cuatrillo
with a comma ( and ) was used to write Mayan languages.


See also

*
Hebrew cantillation Hebrew cantillation is the manner of chanting A chant (from French ', from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the ...
*
Copy editing Copy editing (also known as copyediting and manuscript editing) is the process of revising written material to improve readability and fitness, as well as ensuring that text is free of grammatical and factual errors. ''The Chicago Manual of Style ...
*
English punctuationPunctuation in the English language helps the reader to understand a sentence through visual means other than just the letters of the alphabet. English punctuation has always had two complementary aspects: on the one hand, phonological punctuation li ...
*
Latin-script alphabet A Latin-script alphabet (Latin alphabet or Roman alphabet) is an alphabet that uses Letter (alphabet), letters of the Latin script. The 21-letter archaic Latin alphabet and the 23-letter classical Latin alphabet belong to the oldest of this grou ...
*
List of typographical symbols and punctuation marks This is a list of the most common typographical symbols and punctuation marks used in western European languages. For a far more comprehensive list of symbols and signs, see List of Unicode characters. For other languages and symbol sets (especial ...
*
Ogonek 100px, Ogonek The ( Polish: , "little tail", the diminutive of ; lt, nosinė, "nasal") is a diacritic A diacritic (also diacritical mark, diacritical point, diacritical sign, or accent) is a glyph added to a letter or basic glyph. The t ...

Ogonek
*
Part of speech In traditional grammar A tradition is a belief A belief is an Attitude (psychology), attitude that something is the case, or that some proposition about the world is truth, true. In epistemology, philosophers use the term "belief" to refer t ...
*
Sentence clause structure In grammar In linguistics, the grammar (from Ancient Greek ''grammatikḗ'') of a natural language is its set of structure, structural constraints on speakers' or writers' composition of clause (linguistics), clauses, phrases, and words. The te ...
*
Traditional grammar A tradition is a belief A belief is an attitude Attitude may refer to: Philosophy and psychology * Attitude (psychology) In psychology Psychology is the science of mind and behavior. Psychology includes the study of conscious ...


Related history

*
Global spread of the printing press The global spread of the printing press began with the invention of the printing press A printing press is a mechanical device for applying pressure to an inked surface resting upon a printing, print medium (such as paper or cloth), thereb ...
*
History of printing in East AsiaPrinting Printing is a process for mass reproducing text and images using a master form or template. The earliest non-paper products involving printing include cylinder seals and objects such as the Cyrus Cylinder and the Cylinders of Nabonid ...
* History of sentence spacing * History of Western typography


References


External links


English comma rules
and exercises
Comma guidelines – also helpful for non-native speakers''Grammar, Punctuation, and Capitalization'' – a comprehensive online guide by NASA
– a satirical suggestion to settle the problem of the Oxford Comma once and for all

– another satirical compromise between the American and British traditions relating to quotes and commas.
Top 6 Common Comma Problems Infographic
by Jennifer Frost {{Authority control Punctuation Greek-script diacritics Latin-script diacritics