In political sociology, but also operative within the rest of the animal kingdom, a power structure is a hierarchy of competence or aggression (might) predicated on influence between an individual and other entities in a group. A power structure focuses on the way power and authority is related between people within groups such as a government, nation, institution, organization, or a society. Such structures are of interest to various fields, including sociology, government, economics, and business. A power structure may be formal and intentionally constructed to maximize values like fairness or efficiency, as in a hierarchical organization wherein every entity, except one, is subordinate to a single other entity. Conversely, a power structure may be an informal set of roles, such as those found in a dominance hierarchy in which members of a social group interact, often aggressively, to create a ranking system. A culture that is organised in a dominance hierarchy is a dominator culture, the opposite of an egalitarian culture of partnership. A visible, dominant group or elite that holds power or authority within a power structure is often referred to as being the Establishment. Power structures are fluid, with changes occurring constantly, either slowly or rapidly, evolving or revolutionary, peacefully or violently.