Brackets
() []
brackets (BrE) square brackets (BrE)
round brackets (BrE) brackets (AmE)
parentheses (AmE)
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braces angle brackets
curly braces chevrons
curly brackets (BrE)

A bracket is either of two tall fore- or back-facing punctuation marks commonly used to isolate a segment of text or data from its surroundings.[1] They come in four main pairs of shapes, as given in the box to the right, which also gives their names, that vary between British and American English.[2] Brackets, without further qualification, in British English refers to the (...) marks and in American English the [...] marks.[2][1]

Other symbols are repurposed as brackets in specialist contexts, such as those used by linguists.[3]

Brackets are typically deployed in symmetric pairs, and an individual bracket may be identified as a left or right bracket or, alternatively, an opening or closing bracket,[4] respectively, depending on the directionality of the context.

In casual writing and in some technical fields, such as computing and linguistic analysis, of grammar, brackets nest, with segments of bracketed material containing embedded within them other further bracketed sub-segments.[1] The number of opening brackets matches the number of closing brackets in such cases.[1]

Various forms of brackets are used in mathematics, with specific mathematical meanings, often for denoting specific mathematical functions and subformulas.

History

Angle brackets, or chevrons,  , were the earliest type of bracket to appear in written English. Erasmus coined the term lunula to refer to the round brackets, or (American English) parentheses, ( ), recalling the shape of the crescent moon (Latin: luna).[5]

Most typewriters only had the left and right round brackets. Square brackets appeared with some teleprinters.

Braces (curly brackets) first became part of a character set with the 8-bit code of the IBM 7030 Stretch.[6]

In 1961, ASCII contained parentheses, square, and curly brackets, and also less-than and greater-than signs that could be used as angle brackets.

Typography

In English, typographers mostly prefer not to set brackets in italics, even when the enclosed text is italic.[7] However, in other languages like German, if brackets enclose text in italics, they are usually also set in italics.[8]

Parentheses, or round brackets

The marks ( and ) are parentheses /pəˈrɛnθɪsz/ (singular parenthesis /pəˈrɛnθɪsɪs/) in American English, and either round brackets or simply brackets in British English.[2][3]

In formal writing, "parenthesis" is also used in British English.[20]

Uses of ( )

Parentheses contain adjunctive material that serves to clarify (in the manner of a gloss) or is aside from the main point.[21]

A comma before or after the material can also be used, though if the sentence contains commas for other purposes, visual confusion may result. A dash before and after the material is also sometimes used.

Parentheses may be used in formal writing to add supplementary information, such as "Senator John McCain (R  Arizona) spoke at length". They can also indicate shorthand for "either singular or plural" for nouns, e.g. "the claim(s)". It can also be used for gender-neutral language when one gender adds letters to the other, e.g. "(s)he agreed with his/her physician" (the slash is used in his/her because it replaces letters, not just adds them). It can also be used for converting between the imperial and metric system, e.g. "0 °C (32 °F)".

Parenthetical phrases have been used extensively in informal writing and stream of consciousness literature. Examples include the southern American author William Faulkner (see Absalom, Absalom! and the Quentin section of The Sound and the Fury) as well as poet E. E. Cummings.

Parentheses have historically been used where the em dash is currently used in alternatives[citation needed], such as "parenthesis)(parentheses". Examples of this usage can be seen in editions of Fowler's Dictionary of Modern English Usage.

Parentheses may be nested (generally with one set (such as this) inside another set). This is not commonly used in formal writing (though sometimes other brackets [especially square brackets] will be used for one or more inner sets of parentheses [in other words, secondary {or even tertiary} phrases can be found within the main parenthetical sentence]).

Language

A parenthesis in rhetoric and linguistics refers to the entire bracketed text, not just to the enclosing marks used (so all the text in this set of round brackets may be described as "a parenthesis").[22] Taking as an example the sentence "Mrs. Pennyfarthing (What? Yes, that was her name!) was my landlady.", the explanatory phrase between the parentheses is itself called a parenthesis. Again, the parenthesis implies that the meaning and flow of the bracketed phrase is supplemental to the rest of the text and the whole would be unchanged were the parenthesised sentences removed. The term refers to the syntax rather than the enclosure method: the same clause in the form "Mrs. Pennyfarthing  What? Yes, that was her name!  was my landlady" is also a parenthesis.[23] (In non-specialist usage, the term "parenthetical phrase" is more widely understood.[24])

In phonetics, parentheses are used for indistinguishable[25] or unidentified utterances. They are also seen for silent articulation (mouthing),[26] where the expected phonetic transcription is derived from lip-reading, and with periods to indicate silent pauses, for example (...) or (2 sec).

In some languages, such as the Nicodemus orthography for Coeur d’Alene, parentheses are used as phonemic symbols instead of punctuation.

Enumerations

An unpaired right parenthesis is often used as part of a label in an ordered list, such as this one: