 Gottlob Frege’s notion of a truth value has become part of the standard philosophical and logical terminology. The notion of a truth value is an indispensable instrument of realistic, model-theoretic approaches to semantics. Indeed, truth values play an essential role in applications of model-theoretic semantics in areas such as, for example, knowledge representation and theorem proving based on semantic tableaux, which could not be treated in the present entry. Moreover, considerations on truth values give rise to deep ontological questions concerning their own nature, the feasibility of fact ontologies, and the role of truth values in such ontological theories. There also exist well-motivated theories of generalized truth values that lead far beyond Frege’s classical values the True and the False. (For various directions of further logical and philosophical investigations in the area of truth values see Shramko &amp; Wansing 2009b, 2009c.)