Society is not static. It is, in the terminology of general systems theory, an open system: A dynamic set of interrelated social systems, institutions, and individuals that act upon and react to various aspects of the world around it. Open systems exist in a state of constant flux, continually reacting and adjusting to changing conditions and developments from both within and without the system. Generally, these changes and adjustments are evolutionary-small changes and modifications in a system's structures, interrelationships, or patterns of behavior that better permit social systems to survive in a climate of changing conditions. Occasionally, however, factors or influences may arise whose impact is truly revolutionary, forcing a more abrupt and drastic modification in the social system, resulting in a wholesale transformation in social institutions and relationships.