This document discusses speech act theory, which was proposed by philosophers John Austin and John Searle. They believed that language is used not just to inform but also to perform acts. Austin distinguished three acts in a single speech act: the illocutionary act is the intended function of the utterance, the locutionary act is the literal meaning of words used, and the perlocutionary act is the effect on the listener. Searle later classified illocutionary acts into five categories: directives, commissives, representatives, declaratives, and expressives. The document provides examples to illustrate each category.