Unlike first groups, secondary groups are large groups whose relationships are impersonal and goal oriented. People in a secondary group interact on a less personal level than in a primary group, and their relationships are generally temporary rather than long lasting. Some secondary groups may last for many years, though most are short term. Such groups also begin and end with very little significance in the lives of the people involved.
Secondary relationships involve weak emotional ties and little personal knowledge of one another. In contrast to primary groups, secondary groups don't have the goal of maintaining and developing the relationships themselves.
The distinction between primary and secondary groups was originally proposed by Charles Cooley. He labeled groups as "primary" because people often experience such groups early in their life and such groups play an important role in the development of personal identity. Secondary groups generally develop later in life and are much less likely to be influential on one's identity.
Since secondary groups are established to perform functions, people's roles are more interchangeable. A secondary group is one you have chosen to be a part of. They are based on interests and activities. They are where many people can meet close friends or people they would just call acquaintances. Secondary groups are also groups in which one exchanges explicit commodities, such as labor for wages, services for payments, etc. Examples of these would be employment, vendor-to-client relationships, a doctor, a mechanic, an accountant, and such. A university class, an athletic team, and workers in an office all likely form secondary groups. Primary groups can form within secondary groups as relationships become more personal and close.