For the mathematical structure, see Group (mathematics). In everyday language a group is a set of individuals who form a coherent unit through ongoing relations. Groups vary in size, purpose and permanence but are commonly defined by repeated interaction, shared expectations, and some sense of membership.

Characteristics

Several features commonly identify a group. These include regular interaction or regular contact, shared norms or rules, defined or perceived boundaries, roles for members, and a degree of cohesion or mutual recognition. Groups may also develop traditions, jargon, and informal leadership.

Types and distinctions

  • Primary groups: small, personal, long-term (for example family or close friends).
  • Secondary groups: larger, goal-oriented, more impersonal (for example workplaces or clubs).
  • Formal vs informal: formally organized bodies with explicit rules versus spontaneous social clusters.
  • Reference and membership groups: those people use for self-evaluation versus those they actually belong to.

History and study

Sociology and social psychology developed systematic ways to analyze groups in the late 19th and early 20th centuries. Scholars examined how groups form identity, how social norms emerge, and how group size and structure influence behavior. Empirical studies and theoretical models continue to refine understanding of influence, conformity, leadership, and conflict within groups.

Functions and examples

Groups perform practical and emotional functions: coordinating tasks, distributing labor, transmitting culture, offering social support, and shaping individual attitudes. Common examples include families, work teams, sports squads, voluntary associations, religious congregations and online communities. Each serves different needs and operates under different expectations.

Notable facts and practical implications

Recognizing group properties helps in fields such as management, education, public health and community planning. Interventions that change norms, alter incentives, or restructure roles can shift group behavior. While the term overlaps everyday and technical uses, the social concept of a group is distinct from formal mathematical notions of a group, which study algebraic operations rather than social ties.