In mathematics, the tilde (~) stands for equivalence; for example, a ~ b means "a is equivalent to b" (not equal, but comparable). It also stands for approximation. Officially written as two tildes, one over the other, the single tilde has become acceptable; for example, ~100 means "approximately 100."
In the Unix world, the popular Unix shells, except for the Bourne shell, support a home directory name substitution using the tilde (~). Also called a "squiggle" or "twiddle," the symbol is a prefix. For example, ~ jackson would refer to the "jackson" home directory. See shell
and home directory
In Windows 95/98, the tilde (~) was used to maintain a short version of a long file or folder name for compatibility with Windows 3.1 and DOS. See Win Short file names
In Spanish, the tilde (~) turns the letter "n" into a "nyeh" sound such as in mañana; pronounced "mah-nyah
-nah," which means "tomorrow" and "morning" (tomorrow morning is "mañana por la mañana"). In Portuguese, the tilde over the letters "a" and "o" adds a slight nasal sound to the syllable.