This document defines speech acts and outlines three main types: locutionary, illocutionary, and perlocutionary. It also discusses John Austin's speech act theory and John Searle's classification of five types of illocutionary speech acts: assertives, directives, commissives, expressives, and declarations. Assertives express beliefs, directives try to make the listener perform an action, commissives commit the speaker to future actions, expressives convey feelings, and declarations bring about external changes.