(1) In mathematics, the tilde symbol (~) 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."

(2) In the Unix world, the popular Unix shells, except for the Bourne shell, support a home directory name substitution using the tilde symbol (~). Also called a "squiggle" or "twiddle," the symbol is used as a prefix to a user login name to specify that user's home directory. For example, if your username were "jackson," you would use ~jackson to refer to your home directory. See shell and home directory.

(3) In Windows 95/98, the ~ symbol is used to maintain a short version of a long file or folder name for compatibility with Windows 3.1 and DOS. For example, the short version of a file named "Letter to Joe" would be LETTER~1. Then "Letter to Pat" becomes LETTER~2. See Win Short file names.

(4) The tilde symbol (~) is a Spanish accent that turns the letter "n" into a "nyeh" sound such as in the word mañana, which is pronounced "mah-nyah-nah" and means "tomorrow" and "morning." In fact, tomorrow morning is "mañana por la mañana."