 Intelligent agent, in artificial intelligence, an intelligent agent IA is an autonomous entity which observes through sensors and acts upon an environment using actuators IA is an agent and directs its activity towards achieving goals IA is rational, as defined in economics. Intelligent agents may also learn or use knowledge to achieve their goals. They may be very simple or very complex. The reflex machine, such as a thermostat, is considered an example of an intelligent agent. Intelligent agents are often described schematically as an abstract functional system similar to a computer program. For this reason, intelligent agents are sometimes called abstract intelligent agents AIA citation needed to distinguish them from their real-world implementations as computer systems, biological systems, or organizations. Some definitions of intelligent agents emphasize their autonomy, and so prefer the term autonomous intelligent agents. Several others notably Russell and Norvige 2003 considered goal-directed behavior as the essence of intelligence and so preferred a term borrowed from economics, rational agent. Intelligent agents in artificial intelligence are closely related to agents in economics, and versions of the intelligent agent paradigm are studied in cognitive science, ethics, the philosophy of practical reason, as well as in many interdisciplinary socio-cognitive modeling and computer social simulations. Intelligent agents are also closely related to software agents in autonomous computer programs that carries out tasks on behalf of users. In computer science, the term intelligent agent may be used to refer to a software agent that has some intelligence, regardless if it is not a rational agent by Russell and Norvige's definition. For example, autonomous programs used for operator assistance or data mining sometimes referred to as bots are also called intelligent agents.