Agent

An agent is an entity capable of action in an environment, pursuing goals through perception, decision-making, and action. Agency implies some degree of autonomy and intentionality, though the term spans disciplines from philosophy to everyday usage. An agent may be a living being, a machine, or a software system.

In computer science and artificial intelligence, an intelligent agent perceives its surroundings via sensors, and acts upon the environment using actuators or outputs. It operates according to a program or learned policy, and may be reactive, deliberative, or learning-based. In multi-agent systems, multiple agents interact to achieve individual or common objectives.

In law and business, an agent is a person or entity authorized to act on behalf of another (the principal). This agency relationship creates duties of loyalty and care, and liability may extend to the principal for the agent’s actions performed within the scope of authority. Examples include agents for real estate, sports, or insurance, and professional intermediaries such as travel agents or brokers.

Other uses include the spy or covert operator known as a secret agent; in chemistry, an agent or reagent is a substance that induces a chemical change; in pharmacology, the active agent or active pharmaceutical ingredient is the component that produces the intended effect. In everyday language, agents are often described as actors within systems, markets, or processes.