C.H Cooley an American sociologist introduced the concept of primary group in his book Social Organization. He described the primary groups as those which are characterised by intimate face to face relations, close association and cooperation. Participation in primary group leads to the union of individuals in a common whole. This wholeness involves the sympathy and mutual identification for which the proper expression.
The best examples of primary groups are family, the play group of children and the neighbourhood or community of a group of elders. Primary group is the nucleus of all social organizations. From it originates the human virtues of love, sympathy, cooperation, justice and fairplay.It gives creative expressions to our social impulses .Thus primary groups are those in which we come to know other people intimately as individual personalities. Reference Group was introduced into the literature on small groups by Muzafar Sharif in his textbook An Outline of Social Psychology.
Subsequently this concept was elaborated and modified by sociologists like Turner; Merton.Reference group refers to any group accepted as model or guide for our judgements and actions. In some situations we conform not to the normal to which we actually belong but rather to those of the groups to which we would like to belong, those with which we would like to be identified.