A group is formed when a few or more number of persons collect together on the basis of one or more factors. According to Royal Anthropological Institute the following characteristics of group are:
Mode of acquiring and losing membership by birth ,adoption and marriage on the one hand, by death, by expulsion on misdemeanour, by marriage, by voluntary departure on the other.
Form of the constitution and forms of behaviour distinguishing it from other groups including the rights and duties and the modes of conduct in general prevailing between members of different groups and the relations of groups of the same kind to one another and of different kinds of groups to one another.
Function: The relation of its activities to those of other groups and of the total community.With regard to relations between individuals it should always be ascertained whether they are temporary or permanent. How they are established and what rights and duties and modes of conduct in general they imply.