Speech Act Theory, introduced by philosophers J.L. Austin and J.R. Searle, examines how language is used not only to convey information but to perform actions, such as making requests or giving orders. The theory categorizes speech acts into locutionary, illocutionary, and prelocutionary acts, each serving different communicative functions. It challenges the logical positivist view by demonstrating that language can have meanings and effects beyond mere truth conditions.