Role theory is a concept in sociology and in social psychology that considers most of everyday activity to be the acting-out of socially defined categories (e.g., mother, manager, teacher). Each role is a set of rights, duties, expectations, norms, and behaviors that a person has to face and fulfill. The model is based on the observation that people behave in a predictable way, and that an individual's behavior is context specific, based on social position and other factors. The theatre is a metaphor often used to describe role theory. Although the word role (or roll) has existed in European languages for centuries, as a sociological concept, the term has only been around since the 1920s and 1930s. It became more prominent in sociological discourse through the theoretical works of George Herbert Mead, Jacob L. Moreno, Talcott Parsons, Ralph Linton, and Georg Simmel. Two of Mead's concepts—the mind and the self—are the precursors to role theory. The theory posits the following propositions about social behavior: The division of labor in society takes the form of the interaction among heterogeneous specialized positions that we call roles; Social roles included "appropriate" and "permitted" forms of behavior, guided by social norms, which are commonly known and hence determine expectations; Roles are occupied by individuals, or "actors"; When individuals approve of a social role (i.e., they consider the role "legitimate" and "constructive"), they will incur costs to conform to role norms, and will also incur costs to punish those who violate role norms; Changed conditions can render a social role outdated or illegitimate, in which case social pressures are likely to lead to role change; The anticipation of rewards and punishments, as well as the satisfaction of behaving in a prosocial way, account for why agents conform to role requirements. In terms of differences among role theory, on one side there is a more functional perspective, which can be contrasted with the more micro-level approach of the symbolic interactionist tradition. This type of role theory dictates how closely related individuals' actions are to society, as well as how empirically testable a particular role theory perspective may be. Depending on the general perspective of the theoretical tradition, there are many types of role theory, however, it may be divided into two major types, in particular: structural functionalism role theory and dramaturgical role theory. Structural functionalism role theory is essentially defined as everyone having a place in