: Punctuation
apostrophe ( ’ ' ) brackets ( ( ) ), ( [ ] ), ( { } ), ( < >) colon ( : ) comma ( , ) dashes ( ‒, –, —, ― ) ellipses ( …, ... ) exclamation mark ( ! ) full stop/period ( . ) guillemets ( « » ) hyphen ( -, ‐ ) question mark ( ? ) quotation marks ( ‘ ’, “ ” ) semicolon ( ; ) slash/stroke ( / ) solidus ( ⁄ ) Word dividers spaces ( ) ( ) ( ) ( ) (␠) (␢) (␣) interpunct ( · ) General typography ampersand ( & ) at sign ( @ ) asterisk ( * ) backslash ( \ ) bullet ( • ) caret ( ^ ) copyright symbol ( © ) currency generic: ( ¤ ) specific: ฿, ¢, $, €, ƒ, ₲, ₴, ₭, £, ₦, ¥, ₩, ₪,₮ daggers ( †, ‡ ) degree ( ° ) ditto mark ( 〃 ) inverted exclamation mark ( ¡ ) inverted question mark ( ¿ ) number sign/pound/hash ( # ) numero sign ( № ) ordinal indicator (º, ª) percent (etc.) ( %, ‰, ‱ ) pilcrow ( ¶ ) prime ( ′ ) registered trademark ( ® ) section sign ( § ) service mark ( ℠ ) tilde ( ~ ) trademark ( ™ ) umlaut/diaeresis ( ¨ ) underscore/understrike ( _ ) vertical/pipe/broken bar ( |, ¦ ) Uncommon typography asterism ( ⁂ ) index/fist ( ☞ ) therefore sign ( ∴ ) because sign ( ∵ ) interrobang ( ‽ ) irony mark/percontation point ( ؟ ) lozenge ( ◊ ) reference mark ( ※ ) tie ( ⁀ )
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The colon (:) is a punctuation mark, consisting of two equally sized dots centered on the same vertical line.

Contents 1 Punctuation 1.1 Usage 1.2 Use of capitals 1.3 Spacing 2 History 3 Diacritical usage 4 Word-medial separator 5 Letter 6 Mathematics and logic 7 Computing 8 Internet usage 9 References 10 External links

[edit] Punctuation

[edit] Usage

As with many other punctuation marks, the usage of colon varies among languages and, for a given language, among historical periods. As a rule, however, a colon informs the reader that what follows proves and explains, or simply elements of what is referred to before.

The following classification of the functions that a colon may have, given by Luca Serianni (a pioneer of the colon) for Italian usage,^[1] is generally valid for English and many other languages:

• syntactical-deductive: introduces the logical consequence, or effect, of a fact stated before

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

• syntactical-descriptive: introduces a description—in particular, makes explicit the elements of a set

I have three sisters: Catherine, Sarah, and Mary.

• appositive: introduces a sentence with the role of apposition with respect to the previous one

Luruns could not speak: he was drunk.^[2]

• segmental: introduces a direct speech, in combination with quotation marks and dashes. The segmental function was once a common means of indicating an unmarked quotation on the same line. The following example is from Fowler's grammar book, The King’s English:

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

It is commonly used to introduce speech in a dialogue (such as a script):

Patient: Doctor, I feel like a pair of curtains.
Doctor: Pull yourself together!

A colon may also be used for the following:

• introduction of a definition

A: the first letter in the Latin alphabet

Hypernym of a word: a word having a wider meaning than the given one; e.g., vehicle is a hypernym of car

• separation of the chapter and the verse number(s) indication in many references to religious scriptures, and also epic poems; it was also used for chapter numbers in roman numerals

John 3:14–16 (or John III:14–16) (cf. chapters and verses of the Bible)

The Qur'an, Sura 5:18

• separation of hours, minutes and seconds when reporting the time of day (cf. ISO 8601; alternatively, a period (.) may be used^[3])

The concert finished at 23:45

This file was last modified today at 11:15:05

• separation of a title and the corresponding subtitle

Star Wars Episode IV: A New Hope

• separation of clauses in a periodic sentence

[edit] Use of capitals

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In English, a colon may be followed either by a capital letter or by a lower case letter, depending on usage; where direct speech follows, a capital letter is used; where an acronym or proper noun follows, a capital is used; otherwise, a lower case letter is used.^[3] In British English, the word following the colon is lowercase unless it is a proper noun, an acronym, or if it is normally capitalized for some other reason. Some modern American style guides, including those published by the Associated Press and the Modern Language Association, prescribe capitalization where the colon is followed by an independent clause (i.e. a complete sentence). However, The Chicago Manual of Style^[4] requires capitalization only when the colon introduces two or more complete sentences.^[5]

• Taylor: You know that I have red hair, Chloe. How many more times?
• He is inordinately proud of one article he created: FRESH, UNESCO arose out of his efforts to disambiguate Fresh
• Julian Duguid, author of Green Hell (1931), starts his book boldly: “When a man yields to the urge of Ishmael . . .”
• This theory isn’t as high-falutin’ as it sounds: De Picciotto is just pointing out that, for a tennis player in an important match, it is much easier to shut out an awareness of the plight of the horned owl than to resist the distractions of personal problems. [Peter Bodo, “The Human Side of Steffi Graf,” Tennis, Sept. 1990, p. 46.] ^[6]
• To err is human: to forgive, Divine

In many European languages the colon is usually followed by a lowercase letter (unless the uppercase is due to other reasons, such as a proper noun). However, usage differs from this in German, where an uppercase letter may be used only if the sentence after the colon could stand alone without the preceding sentence (elsewise one may judge freely according to the relative independency of the two assertions),^[7] and in Dutch, where an uppercase letter must be used if the colon is followed by a quotation or an enumeration of complete sentences, although in all other cases a lowercase letter should be used.^[8]

[edit] Spacing

A thin space is traditionally placed before a colon and a thick space after it. In English-language modern high-volume commercial 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. The newer convention (designed for proportional fonts) is that one space is sufficient. See also Double spacing at the end of sentences.

[edit] History

English colon is from Latin colon (plural cola), itself from Greek κῶλον "limb, member, portion", in rhetoric or prosody especially a part or section of a sentence or a rhythmical period of an utterance. In palaeography, a colon is a clause or group of clauses written as a line. The OED cites William Blades' The life and typography of W. Caxton (1882), p. 126: "The Greek grammarians [...] called a complete sentence a period, a limb was a colon, and a clause a comma."

Use of the : symbol to mark the discontinuity of a grammatical construction, or a pause of a length intermediate between that of a semicolon and that of a period, was introduced in English orthography around 1600. John Bullokar's An English expositor (1616) glosses Colon as "A marke of a sentence not fully ended which is made with two prickes."

John Mason in An essay on elocution (1748) prescribes "A Comma Stops the Voice while we may privately tell one, a Semi Colon two; a Colon three: and a Period four."

[edit] Diacritical usage

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 bit 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 (particularly in Mexico) 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. ^[9]

[edit] Word-medial separator

In Finnish and Swedish, the colon can appear inside words in a manner similar to the English apostrophe, between a word (or abbreviation, especially an acronym) and its grammatical (mostly genitive) suffixes. In Swedish, it also occurs in names, for example Antonia Ax:son Johnson (Ax:son for Axelson). In Finnish it is used in loanwords and abbreviations; e.g., USA:han for the illative case of "USA". For loanwords ending orthographically in a consonant but phonetically in a vowel, the apostrophe is used instead: e.g. show'n for the genitive case of the English loan "show" or Versailles'n for the French place name Versailles.

[edit] Letter

The colon is also used as a grammatical tone letter in Budu in the Congo-Kinshasa, 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.^[10] The Unicode character used for the tone letter (U+A789) is different from the punctuation (U+003A).

[edit] Mathematics and logic

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”). Unicode provides a distinct ratio character, Unicode U+2236 (∶) for mathematical usage.

The colon is also used as a division sign: “a divided by b” is written as a : b. However, a vertical line ("a | b") is more common.

The combination with an equal sign, , is used for definitions.

In mathematical logic, when using set-builder notation for describing the characterizing property of a set, it is used as an alternative to a vertical bar, to mean “such that”. Example:

(S is the set of all x in (the real numbers) such that x is strictly greater than 1 and strictly smaller than 3)

In type theory and programming language theory, the colon sign after a term is used to indicate its type, sometimes as a replacement to the symbol. Example:

A colon is also sometimes used to indicate a tensor contraction involving two indices, and a double colon (::) for a contraction over four indices.

[edit] Computing

In computing, the colon character is represented by ASCII code 58, and is located at Unicode code-point U+003A. Scripts comprising wide characters, such as kanji, use a full-width equivalent, ：, located at Unicode code point U+FF1A.

The colon is quite often used as a special control character in URLs, computer programming languages, in the path representation of several file systems (such as HFS), and in many operating systems commands^{[citation needed]}. It is often used as a single post-fix delimiter, signifying a token keyword had immediately preceded it^{[citation needed]} or the transition from one mode of character string interpretation to another related mode^{[citation needed]}. Some applications, such as the widely used MediaWiki, utilize the colon as both a pre-fix and post-fix delimiter.

Several programming languages use the colon for various purposes. In particular, Matlab uses the colon as an binary operator that generates vectors, as well as to select particular portions of existing matrices.

For a double colon see Paamayim Nekudotayim.

[edit] Internet usage

On the Internet a colon, or multiple colons, is sometimes used to denote an action or to emote. In this use it has the inverse function of quotation marks, denoting actions where unmarked text is assumed to be dialogue. For example:

Tom: Pluto is so small, it should not be considered a planet. It is tiny!

Mark: Oh really? ::Drops Pluto on Tom’s head:: Still think it’s small now?

Colons may also be used for sounds, eg. ::Click::, though sounds can also be denoted by an asterisk or other punctuation marks.

Colons are also used to represent two vertically aligned eyes in some emoticons, particularly in Western (English-speaking) cultures. Examples:

:)
:\
:3
D:
:D
:O
:x
:P

[edit] References

[edit] External links

• Some Examples of Colon Usage