A hardware or (more usually) software-based computer system that enjoys the properties of autonomy, social ability, reactivity, and pro-activeness

Agents operate without the direct intervention of humans or others, and have some kind of control over their actions and internal state

Agents interact with other agents (and possibly humans) via some kind of agent communication language

Agents perceive their environment (which may be the physical world, a user via a graphical user interface, a collection of other agents, the Internet, or perhaps all of these combined), and respond in a timely fashion to changes that occur in it

Agents do not simply act in response to their environment, they are able to exhibit goal-directed behaviour by taking the initiative

An agent that interacts with a software environment by issuing commands and interpreting the environment's feedback

The ability of an agent to move around an electronic network

The assumption that an agent will not knowingly communicate false information

The assumption that agents do not have conflicting goals, and that every agent will therefore always try to do what is asked of it

The assumption that an agent will act in order to achieve its goals, and will not act in such a way as to prevent its goals being achieved - at least insofar as its beliefs permit

Specifications addressing how we are to conceptualise agents, what properties agents should have, and how we are to formally represent and reason about these properties

Software engineering models of agents representing the move from specification to implementation, addressing how to construct computer systems that satisfy the properties specified by agent theorists

Programming languages that embody the various principles proposed by theorists, addressing how to program agents and what the right primitives are for this task

A system that is most conveniently described by the intentional stance; one whose simplest consistent description requires the intentional stance

An emergent property of certain complex systems

A hierarchy of task-accomplishing behaviours