{{This article is about| colons in punctuation. For other uses of similar terms, see Colon_(disambiguation) and Colón.}}
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The '''colon''' ("''':'''") is a Punctuation mark, visually consisting of two equally sized dots centered on the same vertical line. Rarely, it is also called "'''dots'''".{{fact}}
==Grammar==
=== 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 of thumb, however, a colon informs the reader that what follows proves, clarifies, explains, or simply enumerates elements of what is referred to before.
The following classification of the functions that a colon may have, given by Luca_Serianni for Italian usage,[{{cite book
| last = Serianni
| first = Luca
| authorlink = Luca Serianni
| coauthors = Castelvecchi, Alberto
| year = 1988
| title = Grammatica italiana. Italiano comune e lingua letteraria. Suoni, forme, costrutti
| publisher = UTET
| location = Turin
| language = Italian
| id = ISBN 88-02-04154-7
}}] is generally valid for English and many other languages:
* '''syntactical-deductive''': introduces the logical consequence, or effect, of a fact stated before
* '''syntactical-descriptive''': introduces a description; in particular, explicits the elements of a set
* '''appositive''': introduces a sentence with the role of Apposition with respect to the previous one
* '''segmental''': introduces a direct Speech, in combination with Quotation_marks and Dashes.
This last was once a common means of indicating an unmarked quotation on the same line (from the Fowlers' grammar book, ''The King's English'')
:Benjamin Franklin proclaimed the virtue of frugality:— A penny saved is a penny earned.
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 when reporting time of the day (cf. ISO_8601)
: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
In English, '''a colon may be followed either by a Capital_letter or by a Lower_case letter''', as the author prefers (unless a capital letter is necessary for a proper noun). No particular consistency is required within a given text, although it is assumed that use of both capital letters and lower case letters after colons, in a single given text, would serve some purpose in communicating the author's desired meaning, rather than simply reflecting carelessness.
=== Conventions and non-English languages ===
In European languages the colon is usually followed by a lowercase letter (again, unless the uppercase is due to other reasons, such as a proper noun). An exception is German, where an uppercase letter must be used if the colon is followed by a complete sentence or a noun, although in all other cases a lowercase letter should be used.
No space is put before a colon, except in French.[''Lexique_des_règles_typographiques_en_usage_à_l'Imprimerie_nationale'', ISBN 2743304820]
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.
==Mathematics==
The colon is also 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 ({{unicode|∶}}) for mathematical usage.
In Logic and, correspondingly, when 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 and only) ''x'' in such that ''x'' is greater than 1 and smaller than 3
In the non-English speaking countries the colon is used as division sign - "a divided by b" is written as a : b.
The combination with an equal sign, , is used for Definitions.
==Phonetics==
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 of a standard colon, pointing toward each other. It is available in Unicode as '''modifier letter triangular colon''', Unicode U+02D0 ({{unicode|ː}}). A regular colon is often used as a fallback when this character is not available.
==Computing==
In Computing, the colon character is represented by ASCII code 58, and is located at Unicode code-point U+003A. The full-width (double-byte) equivalent, '''：''', is located at Unicode code point U+FF1A.
The colon is a special character in URLs, Computer_programming languages, and in the path representation of several File_systems.
==References==
Category:Punctuation
Category:Typography
Da:Kolon
De:Doppelpunkt
Es:Dos_puntos
Eo:Dupunkto
Eu:Bi_puntu_(ikurra)
Fr:Deux-points
Hr:Dvotočje
It:Due_punti
He:נקודתיים
Lt:Dvitaškis
Nl:Dubbele_punt
Ja:コロン_(記号)
No:Kolon
Pl:Dwukropek
Ru:Двоеточие
Sh:Dvotočka
Fi:Kaksoispiste
Sv:Kolon
Zh:冒号