Tilde

The tilde is a diacritic sign consisting of a small wavy line (~) that can appear over or beside letters, or be used as a standalone symbol. In plain text it is represented by the character ~ and has a range of meanings across languages, mathematics, and computing.

In natural languages, the tilde often marks nasalization or related phonetic changes. In Portuguese, it appears as ã and õ to indicate nasalized vowels. In Spanish, the letter ñ represents a palatal nasal sound. Other languages use combining tilde marks above letters to convey nasalization or tonal information, with the combining diacritic U+0303 used in many Unicode representations.

In mathematics and logic, tilde denotes various relations such as similarity or equivalence. It is used in asymptotic notation to indicate a relationship that becomes true in a limit (a ~ b). In computing, the tilde serves as a unary operator for bitwise NOT in languages like C, C++, and JavaScript; in Unix-like systems, a tilde expands to the user’s home directory; in URLs, a tilde can indicate a user directory and is percent-encoded as %7E.

History and typography: The tilde originated in medieval manuscripts as a sign indicating nasalization and over time became a diacritic over letters. The modern Spanish letter ñ arose from n with a tilde. Today, tilde remains a versatile symbol used in linguistics, mathematics, computing, and typography.