Los Tres Cochinitos

The most common use of the colon is to inform the reader that what follows the colon proves, explains, defines, describes, or lists elements of what preceded it. In modern American English usage, a complete sentence precedes a colon, while a list, description, explanation, or definition follows it. The elements which follow the colon may or may not be a complete sentence: since the colon is preceded by a sentence, it is a complete sentence whether what follows the colon is another sentence or not. Some writers prefer to capitalize the first letter after the colon; others do not. Both are correct in American English usage.

colon used before list

Williams was so hungry he ate everything in the house: chips, cold pizza, pretzels and dip, hot dogs, peanut butter and candy.

colon used before a description

Jane is so desperate that she'll date anyone, even Tom: he's uglier than a squashed toad on the highway, and that's on his good days.

colon before definition

For years while I was reading Shakespeare's Othello and criticism on it, I had to constantly look up the word "egregious" since the villain uses that word: outstandingly bad or shocking.

colon before explanation

I had a rough weekend: I had chest pain and spent all Saturday and Sunday in the emergency room.

Some writers use fragments — incomplete sentences — before a colon for emphasis or stylistic preferences (to show a character's Voice in literature), as in this example:

Dinner: chips and beer. What a well-rounded diet I have.

The Bedford Handbook describes several uses of a colon. For example, one can use a colon after an independent clause to direct attention to a list, an appositive or a quotation, and it can be used between independent clauses if the second summarizes or explains the first. In non-literary or non-expository uses, one may use a colon after the salutation in a formal letter, to indicate hours and minutes, to show proportions, between a title and subtitle, and between city and publisher in bibliographic entries.[2]

Luca Serianni, an Italian scholar who helped to define and develop the colon as a punctuation mark, identified four punctuational modes for it: syntactical-deductive, syntactical-descriptive, appositive, and segmental.[3] Although Serianni wrote this guide for the Italian language, his definitions apply also to English and many other languages.

Syntactical-deductive[edit]

The colon introduces the logical consequence, or effect, of a fact stated before.

There was only one possible explanation: the train had never arrived.

Syntactical-descriptive[edit]

In this sense the colon introduces a description; in particular, it makes explicit the elements of a set.

I have three sisters: Daphne, Rose, and Suzanne.

Syntactical-descriptive colons may separate the numbers indicating hours, minutes, and seconds in abbreviated measures of time.[4]

The concert begins at 21:45.

The rocket launched at 09:15:05.

British English, however, more frequently uses a full stop for this purpose:

The programme will begin at 8.00 pm.

You will need to arrive by 14.30.[5]

Appositive[edit]

Bob could not speak: He was drunk.[6]

Bob could not speak: he was drunk.

An appositive colon also separates the subtitle of a work from its principal title. In titles, neither needs to be a complete sentence as it is not expository writing.

Star Wars Episode IV: A New Hope

Segmental[edit]

Like a dash or quotation mark, a segmental colon introduces speech. The segmental function was once a common means of indicating an unmarked quotation on the same line. The following example is from the grammar book The King's English:

Benjamin Franklin proclaimed the virtue of frugality: A penny saved is a penny earned.

This form is still used in written dialogues, such as in a play. The colon indicates that the words following an individual's name are spoken by that individual.

Patient: Doctor, I feel like a pair of curtains.

Doctor: Pull yourself together!

Use of capitals[edit]

Use of capitalization or lower-case after a colon varies. In British English, the word following the colon is in lower case unless it is normally capitalized for some other reason, as with proper nouns and acronyms. British English also capitalizes a new sentence introduced by colon's segmental use; American English goes further and permits writers to similarly capitalize the first word of any independent clause following a colon. This follows the guidelines of some modern American style guides, including those published by the Associated Press and the Modern Language Association. The Chicago Manual of Style,[7] however, requires capitalization only when the colon introduces a direct quotation or two or more complete sentences.[8]

In many European languages, the colon is usually followed by a lower-case letter unless the upper case is required for other reasons, as with British English. German usage, like American English, permits capitalization of independent clauses following a colon.[9] Dutch further capitalizes the first word of any quotation following a colon, even if it is not a complete sentence on its own.[10]

Spacing[edit]

In print, a thin space is traditionally placed before a colon and a thick space after it. In modern English-language printing, no space is placed before a colon and a single space is placed after it. In French-language typing and printing, the traditional rules are preserved.

One or two spaces may be and have been used after a colon. The older convention (designed to be used by monospaced fonts) was to use two spaces after a colon.[11]

See also: Sentence spacing

History[edit]

Further information: Colon (rhetoric)

The English word "colon" is from Latin colon (pl. cola), itself from Ancient Greek κῶλον (kō̂lon), meaning "limb", "member", or "portion". In Greek rhetoric and prosody, the term did not refer to punctuation but to the expression or passage itself. A "colon" was section of a complete thought or passage. From this usage, in palaeography, a colon is a clause or group of clauses written as a line in a manuscript.[12][13]

In the punctuation system devised by Aristophanes of Byzantium in the 3rd century bc, the end of such a clause was thought to occasion a medium-length breath and was marked by a middot ⟨·⟩. (This was only intermittently used, but eventually revived as the ano teleia, the modern Greek semicolon.[14]) A double dot symbol ⟨⁚⟩, meanwhile, later came to be used as a full stop or to mark a change of speaker. A variant was introduced to English orthography around 1600, marking a pause intermediate between a comma and a period.[15] As late as the 18th century, the appropriateness of a colon was still being related to the length of the pause taken when reading the text aloud, but silent reading eventually replaced this with other considerations.[16]

In British English, it was once common for a colon to be followed by a hyphen or dash to indicate a restful pause, in a typographical construction known as the "dog's bollocks", though this usage is now discouraged.[17][18][19]

IPA Diacritical usage[edit]

The IPA length mark

A special triangular colon symbol is used in IPA to indicate that the preceding sound is long. Its form is that of two triangles, each a little larger than a point (dot) of a standard colon, pointing toward each other. It is available in Unicode as modifier letter triangular colon, Unicode U+02D0 (ː). A regular colon is often used as a fallback when this character is not available, and in the practical orthography of some languages which have a phonemic long/short distinction in vowels.

If the upper triangle is used without the lower one, it designates a "half-long" vowel.[20]

Word-medial separator[edit]

In Finnish and Swedish, the colon can appear inside words in a manner similar to the apostrophe in the English possessive case, connecting a grammatical suffix to an abbreviation or initialism, a special symbol, or a digit (e.g., Finnish USA:n and Swedish USA:s for the genitive case of "USA", Finnish %:ssa for the inessive case of "%", or Finnish 20:een for the illative case of "20").

Abbreviation[edit]

In Swedish, the colon is used in contractions, such as S:t for Sankt (Swedish for "Saint"), e.g. in the Stockholm metro station S:t Eriksplan. This can even occur in people's names, for example Antonia Ax:son Johnson (Ax:son for Axelson). The colon was also used to mark abbreviations in early modern English.[21][22]

Letter[edit]

The colon is also used as a grammatical tone letter in Budu in the Democratic Republic of the Congo, in Sabaot in Kenya, in some Grebo in Liberia, and in Papua New Guinea: Erima, Gizra, Go꞉bosi, Gwahatike, Kaluli, Kamula, Kasua, Kuni-Boazi, and Zimakani.[23] The Unicode character used for the tone letter U+A789 ꞉ modifier letter colon is different from the punctuation (U+003A), as well from IPA's triangular colon U+02D0.

Mathematics and logic[edit]

The colon is used in mathematics, cartography, model building and other fields to denote a ratio or a scale, as in 3:1 (pronounced “three to one”). When a ratio is reduced to a

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