Curly brackets { }, also called braces, are a matched pair of grouping symbols. You’ll often see them in mathematics and code. Their exact role depends on the notation or programming language.
Braces in mathematics
In set notation, braces enclose the elements of a set. For example, {2, 4, 6} is the set whose elements are 2, 4, and 6. The commas separate the elements, and the braces identify them as one set.
Braces in code
In JavaScript, braces can group statements into a block. In if (ready) { start(); }, the braces enclose the statement that runs when ready is true. Different languages use different ways to mark a block.
In ordinary prose, parentheses often enclose asides, and square brackets can mark a change inside a quotation.
