The tilde (~) is a character in the standard ASCII character set that is provided on a conventional computer keyboard and is used in both writing and computer programming. It corresponds to ASCII code 126.
The tilde has several uses. In language, it can serve as a modifier for specific letters of the alphabet. In mathematics, the tilde often represents approximation, especially when used in duplicate, and is sometimes called the "equivalency sign." In regular expressions, the tilde is used as an operator in pattern matching, and in C programming, it is used as a bitwise operator representing a unary negation (i.e., "bitwise NOT").
The tilde is one of the most versatile characters on the keyboard. In addition to the above uses, it is also sometimes used to shorten long file names in operating systems. It can be seen either as something that approximates two variables or as something that provides a contrast between them.