Analytic Philosophy is a branch of philosophy that emphasizes clarity and logical analysis. Key figures include Gottlob Frege, Bertrand Russell, and Ludwig Wittgenstein, who contributed to the development of symbolic logic and the philosophy of language. Logical Positivism, emerging from the Vienna Circle, focused on empirical verification and logical necessity. The philosophy of language explores theories of meaning, such as the referential theory, use theory, and speech act theory. Semantic externalism, proposed by Hilary Putnam and Saul Kripke, argues that meaning is influenced by external factors. Ordinary language philosophy, associated with J.L. Austin and later Wittgenstein, analyzes everyday language to resolve philosophical problems. The philosophy of science, with contributions from Karl Popper and Thomas Kuhn, examines the nature of scientific knowledge and methods. W.V.O. Quine's critique of the analytic-synthetic distinction emphasizes the holistic nature of knowledge. Metaphysics in analytic philosophy addresses questions about reality, including the realism vs. anti-realism debate and the nature of properties and universals. Key concepts include propositional logic, predicate logic, and the theory of descriptions.