Comma
The comma is a punctuation mark that appears in several variants in different languages. 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 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 languages, mainly to separate parts of a sentence such as clauses, and items in lists, particularly when there are three or more items listed. The word comma comes from the Greek , which originally meant a cut-off piece; specifically, in grammar, a short clause.
A comma-shaped mark is used as a diacritic in several writing systems and is considered distinct from the cedilla. In Ancient Greek, the rough and smooth breathings appear above the letter. In Latvian, Romanian, and Livonian, the [|comma diacritic] appears below the letter, as in.
For the notation and /x/ used in this article, see grapheme and phoneme respectively.
History
The development of punctuation is much more recent than the alphabet.In the 3rd century BC, Aristophanes of Byzantium invented a system of single dots at varying levels, that separated verses and indicated the amount of breath needed to complete each fragment of the 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 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 known as virgula suspensiva, used from the 13th to 17th centuries to represent a pause. The modern comma was first used by Aldus Manutius.
Moreover, the mark is used to separate words, phrases and clauses in a sentence to help it to be understood: to divide a sentence into easily assimilated bite-sized pieces. However, there are many other functions of the comma, such as 'setting of questions', 'emphasizing point of view', etc.
Uses in English
In general, the comma shows that the words immediately before the comma are less closely or exclusively linked grammatically to those immediately after the comma than they might be otherwise. The comma performs 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.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.
- We cleaned up cores, pits and skins.
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, and "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. It is recommended by the United States Government Printing Office, Harvard University Press, and the classic Elements of Style of Strunk and White.
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 or I spoke to the boys, who are Sam and Tom ;
- I spoke to the boys, Sam, and Tom – must be the boys and Sam and Tom.
- I thank my mother, Anne Smith, and Thomas. This could mean either my mother and Anne Smith and Thomas or my mother, who is Anne Smith; and Thomas. This sentence might be recast as "my mother 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.
suggests that straightforward lists do not need a comma before the final "and", but sometimes it can help the reader. 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, semicolons may be preferred as separators, and the list may be introduced with a colon.
In 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
- 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!
- Mary walked to the party but was unable to walk home.
- I think designer clothes are silly and can't afford them anyway.
- Sit down and shut up.
- She had very little to live on, but she would never have dreamed of taking what was not hers.
The joining of two independent sentences with a comma and no conjunction is known as a comma splice 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, 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 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.
- In this sentence, furthermore, commas would also be called for.
- This sentence is similar; however, a semicolon is necessary as well.
- 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
- 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: 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
- The dull, incessant droning but the cute little cottage.
- The devious lazy red frog suggests there are lazy red frogs, while the devious, lazy red frog does not carry this connotation.
Before quotations
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
and the AP Stylebook,
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 or city and country. Additionally, most style manuals, including The Chicago Manual of Styleand 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 leaving out punctuation when writing addresses on actual letters and packages, as the marks hinder optical character recognition.
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 five or four digits but not in front of the number itself. However, in much of Europe, Southern Africa and Latin America, periods or spaces are used instead; the comma is used as a decimal separator, equivalent to the use in English of the 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 ; 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.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
- 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
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.
- My mother gave me the nickname "Bobby Bobby Bob Bob Boy," which really made me angry.
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.| Character | Unicode point | Unicode name | Notes |
| , | U+002C | Prose in European languages Decimal separator in Continental Europe, Brazil, and some other Latin American countries | |
| ʻ | U+02BB | Used as ʻokina in Hawaiian | |
| ، | U+060C | Used in all languages using Arabic alphabet Also used in other languages, including Syriac and Thaana | |
| ⸲ | U+2E32 | Palaeotype transliteration symbol; indicates nasalization | |
| ⸴ | U+2E34 | ||
| ⹁ | U+2E41 | Used in Sindhi, among others | |
| ⹉ | U+2E49 | Used in the Eastern Orthodox liturgical book Typikon | |
| 、 | U+3001 | Used in Chinese and Japanese writing systems | |
| ︐ | U+FE10 | Used in vertical writing | |
| ︑ | U+FE11 | Used in vertical writing | |
| ﹐ | U+FE50 | ||
| ﹑ | U+FE51 | ||
| ， | U+FF0C | ||
| ､ | U+FF64 |
Some languages use a completely different sort of character for the purpose of the comma.
| Character | Unicode point | Unicode name | Notes |
| · | U+00B7 | Used as a comma in Georgian | |
| ∘ | U+2218 | Used as a comma in Malayalam | |
| ՝ | U+055D | ||
| ߸ | U+07F8 | ||
| ፣ | U+1363 | ||
| ᠂ | U+1802 | ||
| ᠈ | U+1808 | ||
| ⹌ | U+2E4C | ||
| ꓾ | U+A4FE | ||
| ꘍ | U+A60D | ||
| ꛵ | U+A6F5 | ||
| ? | U+1144D | ||
| ? | U+1145A | ||
| ? | U+16E97 | - | |
| ? | U+1DA87 |
There are also a number of comma-like diacritics with "COMMA" in their Unicode names. These do not serve a punctuation function. A comma-like low quotation mark is also available.
| Character | Unicode point | Unicode name | Notes |
| ʽ | U+02BD | Indicates weak aspiration | |
| ̒ | U+0312 | Latvian diacritic cedilla above | |
| ̓ | U+0313 | Greek psili, smooth breathing mark | |
| ̔ | U+0314 | Greek dasia, rough breathing mark | |
| ̕ | U+0315 | ||
| ̦ | U+0326 | Diacritical mark in Romanian, Latvian, Livonian | |
| ‚ | U+201A | Opening single quotation mark in some languages |
Various other Unicode characters combine commas or comma-like figures with other characters, and are not shown here..
Languages other than Western European
uses both commas and interpuncts for lists.In Unicode 5.2.0 "numbers with commas" were added to the Enclosed Alphanumeric Supplement block for compatibility with the ARIB STD B24 character set.
Hebrew script is also written from right to left. However, Hebrew punctuation includes only a regular comma.
Dravidian languages such as Tamil, Telugu, Kannada, and Malayalam also use the punctuation mark in similar usage to that of European languages with similar spacing.
Computing
In the common character encoding systems Unicode and ASCII, character 44 corresponds to the comma symbol. The HTML numeric character reference is,.In many computer languages commas are used as a field delimiter 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 and then returns the value of its evaluated second argument. This is useful in for statements and macros.
In Smalltalk and APL, the comma operator 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, the comma is used to denote Logical Conjunction.
The comma-separated values format is very commonly used in exchanging text data between database and spreadsheet formats.
Diacritical usage
In French, a cedilla is used beneath a, producing, to indicate that the is pronounced like and not like : français, garçon, açaï. Depending on the knowledge and resources of the typist or typesetter, the is irregularly conserved on French words used in English, like façade.The comma is used as a diacritic mark in Romanian 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 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 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, the comma is rotated 180° and placed over the letter. Although their Adobe glyph names are 'letter with comma', their names in the 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 alphabets, the comma is used on the letters,,,, to indicate palatalization in the same fashion as Latvian, except that Livonian uses and represent the same palatal plosive phonemes which Latvian writes as and respectively.
In Czech and Slovak, the diacritic in the characters,, and resembles a superscript comma, but it is used instead of a caron because the letter has an ascender. Other ascender letters with carons, such as letters and , did not modify their carons to superscript commas.
In 16th-century Guatemala, the archaic letter cuatrillo with a comma was used to write Mayan languages.
General
- Copy editing
- Decimal separator
- English punctuation
- Latin-script alphabet
- List of typographical symbols and punctuation marks
- Ogonek
- Part of speech
- Sentence clause structure
- Traditional grammar
Related history
- Global spread of the printing press
- History of printing in East Asia
- History of sentence spacing
- History of Western typography