The Squiggly Diacritic is a diacritical mark, also known as a tilde, which is used in Spanish and Portuguese languages to indicate a nasal sound. It is represented by a wavy line above the letter, usually an 'n' or 'm'. The tilde is also used in mathematics and computer science to indicate a range of values. In linguistics, it is used to indicate a phonetic change in a word. In computing, it is used to represent a special character or symbol.