Typically, every agent makes decisions by solving a well- or ill-defined optimization or choice problem.
For example, buyers (consumers) and sellers (producers) are two common types of agents in partial equilibrium models of a single market.
Each of these agents may play multiple roles in the economy; households, for example, might act as consumers, as workers, and as voters in the model.
[2] The term agent is also used in relation to principal–agent models; in this case, it refers specifically to someone delegated to act on behalf of a principal.
The rules are formulated to model behavior and social interactions based on stipulated incentives and information.