An agent is an autonomous entity with an ontological commitment and agenda of its own.

The term originated in philosophy.

Each agent possesses the ability to act autonomously; this is an important distinction because a simple act of obedience to a command does not qualify an entity as an agent.

Nevertheless in business and in law an agent is often acting on a principal's behalf and has a legal duty to act in that person's best interest.

An agent may interact or negotiate with its environment and/or with other agents. It may make decisions, such as whether to trust and whether to cooperate with others.

• In linguistics, an agent is a noun carrying out an action.
• In microeconomics, an agent is a person who makes a decision on matters affecting the interests of a principal. Principal-agent theory describes appropriate contracts between the two that result in the best interests of the principal being carried through and is an important element of information economics, the theory of labour markets and in executive remuneration.
• Agent (law) - In law an agent is a person authorized to act for another person or organization, with delegated authority, such as a person holding a power of attorney under the law of agency also known as an "attorney_in_fact" in contrast to an "attorney at law". Examples:
  • real estate agent
  • secret agent
  • In publishing, an agent acts for an author to sell their manuscript. Publishers often pay greater attention to manuscripts submitted by an agent than directly (via the slush pile).
  • In music, movies, theatre, show business and sport, agents arrange contracts, appearances and media relations for professionals..
  • In elections in the UK, an election agent is responsible for the conduct of a candidate's campaign.
• The term agent is also used for sentient programs found in the Matrix that battle the humans fighting for freedom. See also software agent.
• Brokers - For some agent-based computer systems, object request brokers (ORBs) complement and speed up the response time of the system, by brokering the requests of the system.