An institution is a humanly devised structure of rules and norms that shape and constrain social behavior. All definitions of institutions generally entail that there is a level of persistence and continuity. Laws, rules, social conventions and norms are all examples of institutions. Institutions vary in their level of formality and informality. Institutions embody a great deal of knowledge of how to do things in society and have been described as the social science equivalent of theories in the natural sciences.