This Handbook contains twenty-nine entries, covering a wide range of topics related to the theory of truth, and its applications in philosophy. It surveys how the concept of truth was understood in ancient and modern philosophy and major debates about truth during the emergence of analytic philosophy. It describes the received standard theories of truth in the current literature, including the coherence, correspondence, identity, and pragmatist theories. It examines the place of truth in metaphysics, focusing on truth-makers, propositions, determinacy, objectivity, deflationism, fictionalism, relativism, and pluralism. It explores broader applications of truth in philosophy, including ethics, science, and mathematics. Finally, it reviews formal work on truth and its application to semantic paradox.