In the social sciences a social group has been defined as two or more people who interact with one another, share similar characteristics, and collectively have a sense of unity. Other theorists disagree however, and are wary of definitions which stress the importance of interdependence or objective similarity. Instead, researchers within the social identity tradition generally define it as "a group is defined in terms of those who identify themselves as members of the group". Regardless, social groups come in a myriad of sizes and varieties. For example, a society can be viewed as a large social group.
Social cohesion approach
A social group exhibits some degree of social cohesion and is more than a simple collection or aggregate of individuals, such as people waiting at a bus stop, or people waiting in a line. Characteristics shared by members of a group may include interests, values, representations, ethnic or social background, and kinship ties. Kinship ties being a social bond based on common ancestry, marriage, or adoption. In a similar vein, some researchers consider the defining characteristic of a group as social interaction. According to Dunbar's number, on average, people cannot maintain stable social relationships with more than 150 individuals.