Curly braces, also known as curly brackets, are punctuation marks used in various programming languages and mathematical expressions. They are represented as and serve to group statements or define a set of elements. In programming, they often indicate the beginning and end of a block of code, helping to organize and structure the code for better readability. In mathematics, curly braces are used to denote sets, which are collections of distinct objects. For example, the set of natural numbers can be represented as 1, 2, 3, .... Curly braces help clarify relationships and operations involving these sets, making them essential in both programming and mathematical contexts.