Brackets, parentheses, and braces are typically used as delimiters in written natural languages, mathematical equations, programming languages, and other formal languages. A 101-key US keyboard has four types:
- ( )
- Parentheses, Round Brackets1
- [ ]
- Square Brackets
- < >
- Angle Brackets
- { }
- Braces, Curly Brackets1
Unfortunately, there is not a universally agreed upon name for the class of these characters. Many people I've talked to call them "brackets" because the word occurs in the name for two of the four delimiters. This is thwarted, however, by another group of people who call square brackets just "brackets" (thereby implying that they are a superclass of angle brackets). Even Computer Science has not adopted a standard name for the class (see "bracket matching" and "paren matching").
1: Alternative naming conventions supplied by Gritchka -- thanks!