In the social sciences, social groups can be categorized based on the various group dynamics that define social organization. In sociological terms, groups can fundamentally be distinguished from one another by the extent to which their nature influence individuals and how. A primary group, for instance, is a small social group whose members share close, personal, enduring relationships with one another (e.g. family, childhood friend). By contrast, a secondary group is one in which interactions are more impersonal than in a primary group and are typically based on shared interests, activities, and/or achieving a purpose outside the relationship itself (e.g. coworkers, schoolmates).

Four basic types of groups have traditionally been recognized: primary groups, secondary groups, collective groups, and categories.

Primary and secondary groups

The distinction between primary and secondary groups serves to identify between two orders of social organization.

Primary groups

A primary group is typically a small social group whose members share close, personal, enduring relationships in which one exchanges implicit items, such as love, caring, concern, support, etc. These groups are often long-lasting and marked by members' concern for one another, where the goal is actually the relationship themselves rather than achieving another purpose. In general, they are also psychologically comforting to the individuals involved, providing a source of support. As such, primary groups or lack thereof play an important role in the development of personal identity, and can be understood as tight circles composed of people such as family, long-term romances, crisis-support group, church group, etc.

Additionally, three sub-groups of primary groups can be also identified:

Categories

Categories are characterized by an aggregate of individuals who share something in common, but only become groups when their similarities have social implications. The degree of entitativity that a group has is influenced by whether a collection of individuals experience the same fate, display similarities, and are close in proximity. If individuals believe that a group is high in entitativity, then they are likely to believe that the group has unchanging characteristics that are essential to the group, known as essentialism.

Reference groups are used in order to evaluate and determine the nature of a given individual or other group's characteristics and sociological attributes. It is the group to which the individual relates or aspires to relate him or herself psychologically. It becomes the individual's frame of reference and source for ordering his or her experiences, perceptions, cognition, and ideas of self. It is important for determining a person's self-identity, attitudes, and social ties. It becomes the basis of reference in making comparisons or contrasts and in evaluating one's appearance and performance.

Reference groups provide the benchmarks and contrast needed for comparison and evaluation of group and personal characteristics. Robert K. Merton hypothesized that individuals compare themselves with reference groups of people who occupy the social role to which the individual aspires.<blockquote>[Merton] developed a theory of the reference group (i.e., the group to which individuals compare themselves, which is not necessarily a group to which those individuals belong), and elaborated on the concepts of in-group and out-group. For any group of people there are always other groups whom they look upon to and aspire to be like them. If, however, the same person considers the relevant reference group to be those in the top 0.1% of households in the US, those making $1.6 million or more, then the individual's income of $80,000 would make them consider themself as rather poor.

Examples

  • Basic groups: The smallest possible social group with a defined number of people (i.e. greater than 1)—often associated with family building:
  • Dyad: Will be a group of two people. Social interaction in a dyad is typically more intense than in larger groups as neither member shares the other's attention with anyone else. (See also couple.)
  • Triad: A group of three people. Triads are generally more stable than dyads because one member can act as a mediator should the relationship between the other two become strained.