An interest is another category for classifying social groups. An ephemeral group for example, is a short-lived group because its underlying interest isn't long lasting. Classes or communities in which the interest is relatively stable have different fates in terms of longevity.

According to the degree of the organization http://essayxxl.com/ , social groups are differentiated from well-organised groups such as state to unorganized group such as crowds.

Social groups based upon awareness of the same kind are divided into in-groups and out-groups. Each social group wherever always has an in-group (inside groups) and an out-group (outside groups). Within an in-group, individuals gain understanding that "we" are different from "they". In means that there is an identity that differentiates whether people belong to in-group or out-group. Common identities within the in-group become "we" or "ours". On the contrary, out-group's identity is employed to identity them as "they" or "theirs".

In-group behavior is generally built upon feelings of sympathy and of the closeness among members of the group. Attitude towards the out-group, on the other hand, is antagonistic or hostile. In-groups or out-groups feeling are often referred to as ethnocentrism.

In-groups and out-groups can be identified in every society, although the underlying interests are not always the same. The number of in-groups and out-groups are small within a traditional society, compared to that within a complex society.