This document discusses different types of agents in artificial intelligence. It defines an agent as anything that can perceive its environment through sensors and act upon the environment through actuators. The document outlines 5 types of agents: 1) Simple reflex agents that act only based on current percepts; 2) Model-based reflex agents that maintain an internal model of the world; 3) Goal-based agents that take actions to reduce distance from a goal; 4) Utility-based agents that choose actions to maximize expected utility; and 5) Learning agents that can improve through learning from experiences.