Institutions are "stable, valued, recurring patterns of behavior". As structures or mechanisms of social order, they govern the behaviour of a set of individuals within a given community. Institutions are identified with a social purpose, transcending individuals and intentions by mediating the rules that govern living behavior.
The term "institution" commonly applies to both informal institutions such as customs, or behavior patterns important to a society, and to particular formal institutions created by entities such as the government and public services. Primary or meta-institutions are institutions such as the family that are broad enough to encompass other institutions.
As structures and mechanisms of social order, institutions are a principal object of study in social sciences such as political science, anthropology, economics, and sociology (the latter described by Émile Durkheim as the "science of institutions, their genesis and their functioning"). Institutions are also a central concern for law, the formal mechanism for political rule-making and enforcement.
People may deliberately create individual, formal organizations commonly identified as "institutions"—but the development and function of institutions in society in general may be regarded as an instance of emergence. That is, institutions arise, develop and function in a pattern of social self-organization beyond conscious intentions of the individuals involved.
As mechanisms of social interaction, institutions manifest in both formal organizations, such as the U.S. Congress, or the Roman Catholic Church, and, also, in informal social order and organization, reflecting human psychology, culture, habits and customs, and encompassing subjective experience of meaningful enactments. Formal institutions are explicitly set forth by a relevant authority and informal institutions are generally unwritten societal rules, norms, and traditions.