Comma (punctuation)
Encyclopedia
The comma is a punctuation
mark. It has the same shape as an apostrophe
or single closing quotation mark
in many typefaces, but it differs from them in being placed on the baseline of the text. Some typeface
s render it as a small line, slightly curved or straight but inclined from the vertical, or with the appearance of a small, filled-in number 9. It is used to separate parts of a sentence (linguistics)
such as clause
s, and lists of three or more things.
The comma is used in many contexts and languages, principally for separating things. According to the Oxford English Dictionary
, the word comma comes directly from the Greek
komma (κόμμα), which means something cut off or a short clause.
invented a system of single dots
(distinctiones) that separated verses (colometry) and indicated the amount of breath needed to complete each fragment of text when reading
aloud. The different lengths were signified by a dot at the bottom, middle, or top of the line. For a short passage (a komma), a media distinctio dot was placed mid-level ( · ). This is the origin of the concept of a comma, though the name came to be used for the mark itself instead of the clause it separated.
The mark used today is descended from a diagonal slash
, or virgula suspensiva ( / ), used from the 13th to 17th centuries to represent a pause, notably by Aldus Manutius
.
structure than they might be otherwise. The comma may be used to perform a number of functions in 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.
(and, or, nor) in a list of more than two elements. A comma used in such a position is called a serial comma
or an Oxford or Harvard comma (after the Oxford University Press
and Harvard University Press
, both prominent advocates of this style). In some cases, use or omission of such a comma may serve to avoid ambiguity:
Use of serial comma disambiguating:
Omission of serial comma disambiguating:
As a rule of thumb
, 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
s may be preferred as separators; and sometimes the list may be introduced with a colon
.
s. In English, a comma is generally used to separate a dependent clause
from the independent clause
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
takes commas if it is non-restrictive
, as in I cut down all the trees, which were over six feet tall. (Without the comma, this would mean that only those trees over six feet tall were cut down.)
Some style guides prescribe that two independent clause
s joined by a coordinating conjunction
(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:
But in the following sentences, where the second clause is dependent (because it cannot stand alone as a sentence), those guides prescribe that the comma be omitted:
However, the comma may be omitted if the second independent clause is very short, typically when the second independent clause is an imperative
. In the following sentences, it is sometimes considered acceptable to omit the comma, even though the second clause is independent:
In some languages, such as German
and Polish
, 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
and is often considered an error in English; in most cases a semicolon should be used instead. A comma splice should not be confused, though, with asyndeton
, a literary device used for a specific effect in which coordinating conjunctions are purposely omitted.
If these adverbs appear in the middle of a sentence, they are enclosed in commas.
Using commas to offset certain adverbs is optional, including then, so, yet, instead, and too (meaning also).
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:
rather than a comma.
Additionally, most style manuals, including The Chicago Manual of Style
and the AP Stylebook
,
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."
was carried out by Italian manned torpedoes."
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
and Royal Mail
recommend writing addresses without any punctuation.
s or spaces are used instead; the comma is used as a decimal separator, equivalent to the use in English of the decimal point. In addition, the comma may not be used for this purpose at all in some number systems, e.g. the SI writing style; a space may be used to separate groups of three digits instead.
pairing can be used in several ways. In American English
, the comma is commonly included inside a quotation, regardless of whether the comma is part of the original quotation. For example:
However, in British English
, punctuation is only placed within quotation marks if it is part of what is being quoted or referred to. Thus:
The use of the serial comma
is sometimes perceived as an Americanism
, but common practice varies in both American and British English. Barbara Child claims that in American English there is a trend toward a decreased use of the comma (Child, 1992, p. 398). This is reinforced by an article by Robert J. Samuelson
in Newsweek
. Lynne Truss
says that this is equally true in the UK, where it has been a slow, steady trend for at least a century:
In his 1963 book "Of Spies and Stratagems", Stanley P. Lovell recalls that, during the Second World War, the British carried the comma over into abbreviations. Specifically, "Special Operations, Executive" was written “S.O.,E.”. Nowadays, even the full stop
s are frequently discarded.
encoding systems Unicode
and ASCII
, character 44 (0x002C
) corresponds to the comma symbol.
In many computer languages commas are used to separate arguments to a function
, to separate elements in a list
and to perform data designation on multiple variables at once.
In the C programming language
the comma symbol is an operator
which evaluates its first argument
(which may have side-effects) and then returns the value of its evaluated second argument. This is useful in for statement
s and macros.
In Smalltalk
, the comma operator is used to concatenate
collections, including strings.
The comma-separated values
(CSV) format is very commonly used in exchanging text data between database and spreadsheet formats.
mark in Romanian
under the s , and under the t . A cedilla
is occasionally used instead of it (notably in the Unicode
glyph names), but this is technically incorrect. The symbol (d with comma below
) was used as part of the Romanian transitional alphabet
(19th century) to indicate the sounds denoted by the Latin letter z
or letters dz, where derived from a Cyrillic
ѕ
(/dz/). The comma and the cedilla are both derivative of a small cursive z placed below the letter. From this standpoint alone, ș, ț, and d̦ could potentially be regarded as stand-ins for sz, tz, and dz respectively.
In Latvian
, the comma is used on the letters ģ, ķ, ļ, ņ, and historically also ŗ, to indicate palatalization
. Because the lowercase letter g has a descender
, the comma is rotated 180° and placed over the letter. Although their Adobe
glyph
names are commas, their names in the Unicode
Standard are g, k, l, n, and r with a cedilla
. They were introduced to the Unicode
standard before 1992, and their name cannot be altered. For input Ģ use Alt 290 and Alt 291 sequences, for Ķ use Alt 310 and Alt 311, for Ļ use Alt 315 and Alt 316, for Ņ use Alt 325 and Alt 326.
In the Czech
and Slovak
languages, the diacritics in the characters ď, ť, and ľ resemble superscript commas, but they are modified caron
s because they have ascender. Other ascender letters with carons, such as letters ȟ (used in Finnish Romani
and Lakota language
s) and ǩ (used in Skolt Sami
language), did not modify their carons to superscript commas.
Punctuation
Punctuation marks are symbols that indicate the structure and organization of written language, as well as intonation and pauses to be observed when reading aloud.In written English, punctuation is vital to disambiguate the meaning of sentences...
mark. It has the same shape as an apostrophe
Apostrophe
The apostrophe is a punctuation mark, and sometimes a diacritic mark, in languages that use the Latin alphabet or certain other alphabets...
or single closing quotation mark
Quotation mark
Quotation marks or inverted commas are punctuation marks at the beginning and end of a quotation, direct speech, literal title or name. Quotation marks can also be used to indicate a different meaning of a word or phrase than the one typically associated with it and are often used to express irony...
in many typefaces, but it differs from them in being placed on the baseline of the text. Some typeface
Typeface
In typography, a typeface is the artistic representation or interpretation of characters; it is the way the type looks. Each type is designed and there are thousands of different typefaces in existence, with new ones being developed constantly....
s render it as a small line, slightly curved or straight but inclined from the vertical, or with the appearance of a small, filled-in number 9. It is used to separate parts of a sentence (linguistics)
Sentence (linguistics)
In the field of linguistics, a sentence is an expression in natural language, and often defined to indicate a grammatical unit consisting of one or more words that generally bear minimal syntactic relation to the words that precede or follow it...
such as clause
Clause
In grammar, a clause is the smallest grammatical unit that can express a complete proposition. In some languages it may be a pair or group of words that consists of a subject and a predicate, although in other languages in certain clauses the subject may not appear explicitly as a noun phrase,...
s, and lists of three or more things.
The comma is used in many contexts and languages, principally for separating things. According to the Oxford English Dictionary
Oxford English Dictionary
The Oxford English Dictionary , published by the Oxford University Press, is the self-styled premier dictionary of the English language. Two fully bound print editions of the OED have been published under its current name, in 1928 and 1989. The first edition was published in twelve volumes , and...
, the word comma comes directly from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
komma (κόμμα), which means something cut off or a short clause.
History
In the 3rd century BC, Aristophanes of ByzantiumAristophanes of Byzantium
Aristophanes of Byzantium was a Greek scholar, critic and grammarian, particularly renowned for his work in Homeric scholarship, but also for work on other classical authors such as Pindar and Hesiod. Born in Byzantium about 257 BC, he soon moved to Alexandria and studied under Zenodotus,...
invented a system of single dots
Interpunct
An interpunct —also called an interpoint—is a small dot used for interword separation in ancient Latin script, which also appears in some modern languages as a stand-alone sign inside a word. It is present in Unicode as code point ....
(distinctiones) that separated verses (colometry) and indicated the amount of breath needed to complete each fragment of text when reading
Reading (process)
Reading is a complex cognitive process of decoding symbols for the intention of constructing or deriving meaning . It is a means of language acquisition, of communication, and of sharing information and ideas...
aloud. The different lengths were signified by a dot at the bottom, middle, or top of the line. For a short passage (a komma), a media distinctio dot was placed mid-level ( · ). This is the origin of the concept of a comma, though the name came to be used for the mark itself instead of the clause it separated.
The mark used today is descended from a diagonal slash
Slash (punctuation)
The slash is a sign used as a punctuation mark and for various other purposes. It is now often called a forward slash , and many other alternative names.-History:...
, or virgula suspensiva ( / ), used from the 13th to 17th centuries to represent a pause, notably by Aldus Manutius
Aldus Manutius
Aldus Pius Manutius , the Latinised name of Aldo Manuzio —sometimes called Aldus Manutius, the Elder to distinguish him from his grandson, Aldus Manutius, the Younger—was an Italian humanist who became a printer and publisher when he founded the Aldine Press at Venice.His publishing legacy includes...
.
Uses
In general, the comma is used where ambiguity might otherwise arise, to indicate an interpretation of the text such that the words immediately before and after the comma are less closely or exclusively linked in the associated grammaticalGrammar
In linguistics, grammar is the set of structural rules that govern the composition of clauses, phrases, and words in any given natural language. The term refers also to the study of such rules, and this field includes morphology, syntax, and phonology, often complemented by phonetics, semantics,...
structure than they might be otherwise. The comma may be used to perform a number of functions in English
English language
English is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...
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.
In lists
Commas are used to separate items in lists, as in They own a cat, a dog, two rabbits, and six mice. In English, a comma may or may not be used before the final conjunctionGrammatical conjunction
In grammar, a conjunction is a part of speech that connects two words, sentences, phrases or clauses together. A discourse connective is a conjunction joining sentences. This definition may overlap with that of other parts of speech, so what constitutes a "conjunction" must be defined for each...
(and, or, nor) in a list of more than two elements. A comma used in such a position is called a serial comma
Serial comma
The serial comma is the comma used immediately before a coordinating conjunction preceding the final item in a list of three or more items...
or an Oxford or Harvard comma (after the Oxford University Press
Oxford University Press
Oxford University Press is the largest university press in the world. It is a department of the University of Oxford and is governed by a group of 15 academics appointed by the Vice-Chancellor known as the Delegates of the Press. They are headed by the Secretary to the Delegates, who serves as...
and Harvard University Press
Harvard University Press
Harvard University Press is a publishing house established on January 13, 1913, as a division of Harvard University, and focused on academic publishing. In 2005, it published 220 new titles. It is a member of the Association of American University Presses. Its current director is William P...
, both prominent advocates of this style). In some cases, use or omission of such a comma may serve to avoid ambiguity:
Use of serial comma disambiguating:
- I spoke to the boys, Sam and Tom. – could be either the boys and Sam and Tom (I spoke to more than three people) or 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)
Omission of serial comma disambiguating:
- I thank my mother, Anne Smith, and Thomas. – could be either my mother and Anne Smith and Thomas (three people) or my mother, who is Anne Smith, and Thomas (two people)
- I thank my mother, Anne Smith and Thomas. – The writer is thanking three people: the writer's mother and Anne Smith (who is not the writer's mother) and Thomas.
As a rule of thumb
Rule of thumb
A rule of thumb is a principle with broad application that is not intended to be strictly accurate or reliable for every situation. It is an easily learned and easily applied procedure for approximately calculating or recalling some value, or for making some determination...
, The Guardian
The Guardian
The Guardian, formerly known as The Manchester Guardian , is a British national daily newspaper in the Berliner format...
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
Semicolon
The semicolon is a punctuation mark with several uses. The Italian printer Aldus Manutius the Elder established the practice of using the semicolon to separate words of opposed meaning and to indicate interdependent statements. "The first printed semicolon was the work of ... Aldus Manutius"...
s may be preferred as separators; and sometimes the list may be introduced with a colon
Colon (punctuation)
The colon is a punctuation mark consisting of two equally sized dots centered on the same vertical line.-Usage:A colon informs the reader that what follows the mark proves, explains, or lists elements of what preceded the mark....
.
Separation of clauses
Commas are often used to separate clauseClause
In grammar, a clause is the smallest grammatical unit that can express a complete proposition. In some languages it may be a pair or group of words that consists of a subject and a predicate, although in other languages in certain clauses the subject may not appear explicitly as a noun phrase,...
s. In English, a comma is generally used to separate a dependent clause
Dependent clause
In linguistics, a dependent clause is a clause that augments an independent clause with additional information, but which cannot stand alone as a sentence. Dependent clauses modify the independent clause of a sentence or serve as a component of it...
from the independent clause
Independent clause
An independent clause is a clause that can stand by itself, also known as a simple sentence. An independent clause contains a subject and a predicate; it makes sense by itself....
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
Relative clause
A relative clause is a subordinate clause that modifies a noun phrase, most commonly a noun. For example, the phrase "the man who wasn't there" contains the noun man, which is modified by the relative clause who wasn't there...
takes commas if it is non-restrictive
Restrictiveness
In semantics, a modifier is said to be restrictive if it restricts the reference of its head. For example, in "the red car is fancier than the blue one", red and blue are restrictive, because they restrict which cars car and one are referring to...
, as in I cut down all the trees, which were over six feet tall. (Without the comma, this would mean that only those trees over six feet tall were cut down.)
Some style guides prescribe that two independent clause
Independent clause
An independent clause is a clause that can stand by itself, also known as a simple sentence. An independent clause contains a subject and a predicate; it makes sense by itself....
s joined by a coordinating conjunction
Grammatical conjunction
In grammar, a conjunction is a part of speech that connects two words, sentences, phrases or clauses together. A discourse connective is a conjunction joining sentences. This definition may overlap with that of other parts of speech, so what constitutes a "conjunction" must be defined for each...
(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!
But in the following sentences, where the second clause is dependent (because it cannot stand alone as a sentence), 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.
- Don't push that button or set off the twelve tons of high explosives sitting right under our feet.
However, the comma may be omitted if the second independent clause is very short, typically when the second independent clause is an imperative
Imperative mood
The imperative mood expresses commands or requests as a grammatical mood. These commands or requests urge the audience to act a certain way. It also may signal a prohibition, permission, or any other kind of exhortation.- Morphology :...
. In the following sentences, it is sometimes considered acceptable to omit the comma, even though the second clause is independent:
- Sit down and shut up.
- Run to the end of the diving board and jump.
- Come over here and kiss me.
In some languages, such as German
German language
German is a West Germanic language, related to and classified alongside English and Dutch. With an estimated 90 – 98 million native speakers, German is one of the world's major languages and is the most widely-spoken first language in the European Union....
and Polish
Polish language
Polish is a language of the Lechitic subgroup of West Slavic languages, used throughout Poland and by Polish minorities in other countries...
, 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
Comma splice
A comma splice is the use of a comma to join two independent clauses. For example:Although acceptable in some languages and compulsory in others, comma splices are usually considered style errors in English.- Prescriptive view :...
and is often 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
Asyndeton is a stylistic scheme in which conjunctions are deliberately omitted from a series of related clauses. Examples are veni, vidi, vici and its English translation "I came, I saw, I conquered." Its use can have the effect of speeding up the rhythm of a passage and making a single idea more...
, 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 adverbs, 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 enclosed in commas.
- In this sentence, furthermore, commas would also be called for.
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 parentheticalParenthesis (rhetoric)
In rhetoric, a parenthesis is an explanatory or qualifying word, clause, or sentence inserted into a passage with which it doesn't necessarily have any grammatical connection...
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.
- AppositiveAppositionApposition is a grammatical construction in which two elements, normally noun phrases, are placed side by side, with one element serving to define or modify the other. When this device is used, the two elements are said to be in apposition...
: 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; that is, 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 quotes
A comma is used to set off quoted material that is the grammatical object of an active verb of speaking or writing, as in Mr. Kershner says, "You should know how to use a comma." Quotations that follow and support an assertion should be set off by a colonColon (punctuation)
The colon is a punctuation mark consisting of two equally sized dots centered on the same vertical line.-Usage:A colon informs the reader that what follows the mark proves, explains, or lists elements of what preceded the mark....
rather than a comma.
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 necessary because of the otherwise confusing consecutive numbers, compare December 19 1941.Additionally, most style manuals, including The Chicago Manual of Style
The Chicago Manual of Style
The Chicago Manual of Style is a style guide for American English published since 1906 by the University of Chicago Press. Its 16 editions have prescribed writing and citation styles widely used in publishing...
and the AP Stylebook
AP Stylebook
The Associated Press Stylebook and Briefing on Media Law, usually called the AP Stylebook, is a style and usage guide used by newspapers and in the news industry in the United States...
,
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: "On 19 December 1941 the Raid on AlexandriaRaid on Alexandria (1941)
The Raid on Alexandria was carried out on 19 December 1941 by Italian Navy forces attacking Royal Navy forces in the harbour of Alexandria.-Background:...
was carried out by Italian manned torpedoes."
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 StyleThe Chicago Manual of Style
The Chicago Manual of Style is a style guide for American English published since 1906 by the University of Chicago Press. Its 16 editions have prescribed writing and citation styles widely used in publishing...
and the AP Stylebook
AP Stylebook
The Associated Press Stylebook and Briefing on Media Law, usually called the AP Stylebook, is a style and usage guide used by newspapers and in the news industry in the United States...
,
recommend that the second element be treated as a parenthetical, requiring a second comma after: "The plane landed in Kampala, Uganda
Uganda
Uganda , officially the Republic of Uganda, is a landlocked country in East Africa. Uganda is also known as the "Pearl of Africa". It is bordered on the east by Kenya, on the north by South Sudan, on the west by the Democratic Republic of the Congo, on the southwest by Rwanda, and on the south by...
, that evening."
The United States Postal Service
United States Postal Service
The United States Postal Service is an independent agency of the United States government responsible for providing postal service in the United States...
and Royal Mail
Royal Mail
Royal Mail is the government-owned postal service in the United Kingdom. Royal Mail Holdings plc owns Royal Mail Group Limited, which in turn operates the brands Royal Mail and Parcelforce Worldwide...
recommend writing addresses without any punctuation.
In numbers
In representing large numbers, English texts usually use commas to separate each group of three digits. This is almost always done for numbers of six or more digits, and often for five or four digits. However, in much of Europe, Southern Africa and Latin America periodPeriod
Period may mean a full stop: a punctuation in American-English.Period or periodic may also refer to:-Science:* Orbital period, a concept in astronomy...
s or spaces are used instead; the comma is used as a decimal separator, equivalent to the use in English of the decimal point. In addition, the comma may not be used for this purpose at all in some number systems, e.g. the SI writing style; a space may be used to separate groups of three digits instead.
In names
Commas are used when writing names that are presented surname first: Smith, John. They are also used before many titles that follow a name: John Smith, Ph.D.Ellipsis
Commas may be used to indicate that a word 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.
Differences between American and British usage
The comma and the quotation markQuotation mark
Quotation marks or inverted commas are punctuation marks at the beginning and end of a quotation, direct speech, literal title or name. Quotation marks can also be used to indicate a different meaning of a word or phrase than the one typically associated with it and are often used to express irony...
pairing can be used in several ways. In American English
American English
American English is a set of dialects of the English language used mostly in the United States. Approximately two-thirds of the world's native speakers of English live in the United States....
, the comma is commonly included inside a quotation, regardless of whether the comma is part of the original quotation. For example:
- My mother gave me the nickname "Johnny Boy," which really made me angry.
However, in British English
British English
British English, or English , is the broad term used to distinguish the forms of the English language used in the United Kingdom from forms used elsewhere...
, punctuation is only placed within quotation marks if it is part of what is being quoted or referred to. Thus:
- My mother gave me the nickname "Johnny Boy", which really made me angry.
The use of the serial comma
Serial comma
The serial comma is the comma used immediately before a coordinating conjunction preceding the final item in a list of three or more items...
is sometimes perceived as an Americanism
American English
American English is a set of dialects of the English language used mostly in the United States. Approximately two-thirds of the world's native speakers of English live in the United States....
, but common practice varies in both American and British English. Barbara Child claims that in American English there is a trend toward a decreased use of the comma (Child, 1992, p. 398). This is reinforced by an article by Robert J. Samuelson
Robert J. Samuelson
Robert Jacob Samuelson is a contributing editor of Newsweek and The Washington Post where he has written about business and economic issues since 1977. His columns appear in both publications. His articles also appear in the Los Angeles Times, The Boston Globe, and other influential newspapers...
in Newsweek
Newsweek
Newsweek is an American weekly news magazine published in New York City. It is distributed throughout the United States and internationally. It is the second-largest news weekly magazine in the U.S., having trailed Time in circulation and advertising revenue for most of its existence...
. Lynne Truss
Lynne Truss
Lynne Truss is an English writer and journalist, best known for her popular book Eats, Shoots & Leaves: The Zero Tolerance Approach to Punctuation.-Early life:...
says that this is equally true in the UK, where it has been a slow, steady trend for at least a century:
In his 1963 book "Of Spies and Stratagems", Stanley P. Lovell recalls that, during the Second World War, the British carried the comma over into abbreviations. Specifically, "Special Operations, Executive" was written “S.O.,E.”. Nowadays, even the full stop
Full stop
A full stop is the punctuation mark commonly placed at the end of sentences. In American English, the term used for this punctuation is period. In the 21st century, it is often also called a dot by young people...
s are frequently discarded.
Computing
In the common characterCharacter (computing)
In computer and machine-based telecommunications terminology, a character is a unit of information that roughly corresponds to a grapheme, grapheme-like unit, or symbol, such as in an alphabet or syllabary in the written form of a natural language....
encoding systems Unicode
Unicode
Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...
and ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
, character 44 (0x002C
Hexadecimal
In mathematics and computer science, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F to represent values ten to fifteen...
) corresponds to the comma symbol.
In many computer languages commas are used to separate arguments to a function
Subroutine
In computer science, a subroutine is a portion of code within a larger program that performs a specific task and is relatively independent of the remaining code....
, to separate elements in a list
Array data type
In computer science, an array type is a data type that is meant to describe a collection of elements , each selected by one or more indices that can be computed at run time by the program. Such a collection is usually called an array variable, array value, or simply array...
and to perform data designation on multiple variables at once.
In the C programming language
C (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
the comma symbol is an operator
Comma operator
In the C and C++ programming languages, the comma operator is a binary operator that evaluates its first operand and discards the result, and then evaluates the second operand and returns this value...
which evaluates its first argument
Parameter (computer science)
In computer programming, a parameter is a special kind of variable, used in a subroutine to refer to one of the pieces of data provided as input to the subroutine. These pieces of data are called arguments...
(which may have side-effects) and then returns the value of its evaluated second argument. This is useful in for statement
Statement (programming)
In computer programming a statement can be thought of as the smallest standalone element of an imperative programming language. A program written in such a language is formed by a sequence of one or more statements. A statement will have internal components .Many languages In computer programming...
s and macros.
In Smalltalk
Smalltalk
Smalltalk is an object-oriented, dynamically typed, reflective programming language. Smalltalk was created as the language to underpin the "new world" of computing exemplified by "human–computer symbiosis." It was designed and created in part for educational use, more so for constructionist...
, the comma operator is used to concatenate
Concatenation
In computer programming, string concatenation is the operation of joining two character strings end-to-end. For example, the strings "snow" and "ball" may be concatenated to give "snowball"...
collections, including strings.
The comma-separated values
Comma-separated values
A comma-separated values file stores tabular data in plain-text form. As a result, such a file is easily human-readable ....
(CSV) format is very commonly used in exchanging text data between database and spreadsheet formats.
Diacritical usage
The comma is used as a diacriticDiacritic
A diacritic is a glyph added to a letter, or basic glyph. The term derives from the Greek διακριτικός . Diacritic is both an adjective and a noun, whereas diacritical is only an adjective. Some diacritical marks, such as the acute and grave are often called accents...
mark in Romanian
Romanian language
Romanian Romanian Romanian (or Daco-Romanian; obsolete spellings Rumanian, Roumanian; self-designation: română, limba română ("the Romanian language") or românește (lit. "in Romanian") is a Romance language spoken by around 24 to 28 million people, primarily in Romania and Moldova...
under the s , and under the t . A cedilla
Cedilla
A cedilla , also known as cedilha or cédille, is a hook added under certain letters as a diacritical mark to modify their pronunciation.-Origin:...
is occasionally used instead of it (notably in the Unicode
Unicode
Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...
glyph names), but this is technically incorrect. The symbol (d with comma below
D-comma
is a letter which was part of the Romanian alphabet, and used to represent the sound or where it was derived from a Latin d...
) was used as part of the Romanian transitional alphabet
Romanian alphabet
The Romanian alphabet is a modification of the Latin alphabet and consists of 31 letters:The letters Q , W , and Y were officially introduced in the Romanian alphabet in 1982, although they had been used earlier...
(19th century) to indicate the sounds denoted by the Latin letter z
Z
Z is the twenty-sixth and final letter of the basic modern Latin alphabet.-Name and pronunciation:In most dialects of English, the letter's name is zed , reflecting its derivation from the Greek zeta but in American English, its name is zee , deriving from a late 17th century English dialectal...
or letters dz, where derived from a Cyrillic
Cyrillic alphabet
The Cyrillic script or azbuka is an alphabetic writing system developed in the First Bulgarian Empire during the 10th century AD at the Preslav Literary School...
ѕ
Dze
Dze is a letter of the Cyrillic alphabet, used in the Macedonian language to represent the voiced alveolar affricate , pronounced like ⟨ds⟩ in "pods"....
(/dz/). The comma and the cedilla are both derivative of a small cursive z placed below the letter. From this standpoint alone, ș, ț, and d̦ could potentially be regarded as stand-ins for sz, tz, and dz respectively.
In Latvian
Latvian language
Latvian is the official state language of Latvia. It is also sometimes referred to as Lettish. There are about 1.4 million native Latvian speakers in Latvia and about 150,000 abroad. The Latvian language has a relatively large number of non-native speakers, atypical for a small language...
, the comma is used on the letters ģ, ķ, ļ, ņ, and historically also ŗ, to indicate palatalization
Palatalization
In linguistics, palatalization , also palatization, may refer to two different processes by which a sound, usually a consonant, comes to be produced with the tongue in a position in the mouth near the palate....
. Because the lowercase letter g has a descender
Descender
In typography, a descender is the portion of a letter that extends below the baseline of a font. The line that descenders reach down to is known as the beard line....
, the comma is rotated 180° and placed over the letter. Although their Adobe
Adobe Systems
Adobe Systems Incorporated is an American computer software company founded in 1982 and headquartered in San Jose, California, United States...
glyph
Glyph
A glyph is an element of writing: an individual mark on a written medium that contributes to the meaning of what is written. A glyph is made up of one or more graphemes....
names are commas, their names in the Unicode
Unicode
Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...
Standard are g, k, l, n, and r with a cedilla
Cedilla
A cedilla , also known as cedilha or cédille, is a hook added under certain letters as a diacritical mark to modify their pronunciation.-Origin:...
. They were introduced to the Unicode
Unicode
Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...
standard before 1992, and their name cannot be altered. For input Ģ use Alt 290 and Alt 291 sequences, for Ķ use Alt 310 and Alt 311, for Ļ use Alt 315 and Alt 316, for Ņ use Alt 325 and Alt 326.
In the Czech
Czech language
Czech is a West Slavic language with about 12 million native speakers; it is the majority language in the Czech Republic and spoken by Czechs worldwide. The language was known as Bohemian in English until the late 19th century...
and Slovak
Slovak language
Slovak , is an Indo-European language that belongs to the West Slavic languages .Slovak is the official language of Slovakia, where it is spoken by 5 million people...
languages, the diacritics in the characters ď, ť, and ľ resemble superscript commas, but they are modified caron
Caron
A caron or háček , also known as a wedge, inverted circumflex, inverted hat, is a diacritic placed over certain letters to indicate present or historical palatalization, iotation, or postalveolar pronunciation in the orthography of some Baltic, Slavic, Finno-Lappic, and other languages.It looks...
s because they have ascender. Other ascender letters with carons, such as letters ȟ (used in Finnish Romani
Romani language
Romani or Romany, Gypsy or Gipsy is any of several languages of the Romani people. They are Indic, sometimes classified in the "Central" or "Northwestern" zone, and sometimes treated as a branch of their own....
and Lakota language
Lakota language
Lakota is a Siouan language spoken by the Lakota people of the Sioux tribes. While generally taught and considered by speakers as a separate language, Lakota is mutually understandable with the other two languages , and is considered by most linguists one of the three major varieties of the Sioux...
s) and ǩ (used in Skolt Sami
Skolt Sami
Skolt Sami is a Uralic, Sami language spoken by approximately 400 speakers in Finland, mainly in Sevettijärvi, and approximately 20–30 speakers of the Njuõˊttjäuˊrr dialect in an area surrounding Lake Lovozero in Russia. Skolt Sami used to also be spoken on the Neiden area of Norway,...
language), did not modify their carons to superscript commas.
External links
- Commas: They're Not Just for English Majors, Anymore
- English comma rules and exercises
- Major Comma Uses
- Notes on Commas
- Comma guidelines – also helpful for non-native speakers
- Grammar, Punctuation, and Capitalization – a comprehensive online guide by NASA
- The Oxford Comma: A Solution – a satirical suggestion to settle the problem of the Oxford Comma once and for all.
- The Quotta and the Quottiod – another satirical compromise between the American and British traditions relating to quotes and commas.
- The Ten Functions of Commas in English