Although the term "agent" has come to mean many things, it perhaps has the most traction when identified with an anthropomorphized and autonomous program that acts as a personal assistant to a specific user (or set of users). In this model, the agent usually "lives" in a virtual world, may have access to data about its user, and is empowered to act on its user's behalf in a variety of computer-based tasks, including appointment scheduling, vetting messages, engaging in negotiation with other users, discovering items of interest, and even initiating contact with other users and agents.