The ecological systems model is made up of concentric circles with the individual at the center. The widening circles indicate the level of influence on the individual. Going from the most immediate influence (at the center) to the furthest, the systems are the microsystem (family, school, and others who interact intimately with the individual), the mesosystem (made up of interactions between the community and the family), the exosystem (which includes extended family and other community members), the macrosystem (which includes cultural, political, and economic forces), and the chronosystem (which is socio-historic changes and time as it affects both society and the individual). The model is useful for understanding the family as a dynamic and ever-changing social unit that is influenced by many forces from immediate, daily interactions to those of the political changes and the course of time.