agent, environment, sensors, percept, percept sequence, agent function, action, observation, state, decision An agent through sensors percept is anything that can be viewed as perceiving its environment state and acting upon that environment through actuators. We use the term to refer to the content an agent's sensors are perceiving. An agent's is the complete history of everything the agent has ever perceived. In general, an agent's choice of action at any given instant can depend on its built-in knowledge and on the entire percept sequence observed to date, but not on anything it hasn't perceived. By specifying the agent's choice of action for every possible percept sequence, we have said more or less everything there is to say about the agent. Mathematically speaking, we say that an agent's behavior is described by the agent function that maps any given observation to an action