Understanding Truth aims to illuminate the notion of truth, and the role it plays in our ordinary thought, as well as in our logical, philosophical, and scientific theories. Part one is concerned with substantive background issues: the identification of the bearers of truth, the basis for distinguishing truth from other notions, like certainty, with which it is often confused, and the formulation of positive responses to well-known forms of philosophical skepticism about truth. Part two explicates the formal theories of Alfred Tarski and Saul Kripke, including their treatments of the Liar paradox, and evaluates the philosophical significance of their work. Part three extends important lessons drawn from Tarski and Kripke to new domains: vague predicates, the Sorites paradox, and the development of a larger, deflationary perspective on truth. Part one attempts to diffuse five different forms of truth skepticism, broadly conceived: the view that truth is indefinable, that it is unknowable, that it is inextricably metaphysical, that there is no such thing as truth, and the view that truth is inherently paradoxical, and so must either be abandoned, or revised. An intriguing formulation of the last of these views is due to Alfred Tarski, who argued that the Liar paradox shows natural languages to be inconsistent because they contain defective, and ultimately incoherent, truth predicates. I argue in response that on a plausible interpretation of his puzzling notion of an inconsistent language, Tarski’s argument turns out to be logically valid, but almost certainly unsound, since one of its premises can be seen to be indefensible. Similar results are achieved for other forms of truth skepticism.