A performance measure embodies the criterion for the success of an agent’s behavior. When an agent is plunked down in an environment, it generates a sequence of actions according to the percepts it receives. This sequence of actions causes the environment to go through the sequence of states. If the sequence is desirable, then the agent has performed well. Obviously there is not one fixed measure suitable for all agents. It is better to design performance measures according to what one actually wants in the environment, rather than according to how one thinks the agent should act.