parentheses

Parentheses are punctuation marks consisting of a pair of curved symbols: an opening parenthesis, (, and a closing parenthesis, ). They are used to enclose material that is supplementary to the main text. The term parentheses (plural) or parenthesis (singular) refers to the pair as a unit or to either one of the marks individually. The word derives from Greek parénthesis, meaning insertion.

In written English, parentheses enclose items such as clarifications, asides, or references. Material inside parentheses is typically considered optional for the surrounding sentence. Punctuation rules vary: in American style, if the parenthetical material is a complete sentence, the period tends to go inside the closing parenthesis; otherwise, it generally goes outside. The use of parentheses can affect readability, signaling that the enclosed material is tangential or supplementary.

In mathematics and related disciplines, parentheses indicate grouping and function application, and they influence the order of operations. They are used to denote intervals and coordinate notation as well. In computing and programming, parentheses enclose function arguments and control the evaluation order of expressions; in some languages, they also participate in creating tuples or parameter lists.

Other bracket characters include square brackets [ ], curly braces { }, and angle brackets ⟨ ⟩, each serving distinct syntactic purposes in various fields. The term brackets is a broader category, but parentheses specifically refer to the curved marks described here. Nested or alternating use of parentheses and other brackets is common in technical writing and mathematics to organize complex expressions.