A man is social animal, who can’t live in isolation; most of the routine activity that a man performs is in group. Therefore a social group is collections of human beings.

According to Bogardus – A social groups may be thought of a number of persons, two or more, who have some common objects of attentions who are stimulating to each other, who have common loyalties and participate in similar activities.

Horton and Hunt –Groups are aggregates of categories of people who have consciousness of membership and of interaction.

Characteristics of Social Group ;-

(1) Mutual relationship – The groups members are interrelated to each other. A gathering of individuals forms a social group only when they are interrelated.
(2) Senses of unity – The members of a group are united by a sense of unity and a feeling of sympathy.
(3) We feeling – The members of a groups help each other and defend their interest collectively.
(4) Common Interests :- The interests of the groups members are common. It is for the realization of the common interest that they meet together.
(5) Similar Behaviour :- The members of a groups behave in a similar way to achieve common interest.
(6) Group Norms – Every group has its own rules or norms which the members are supposed to follow.

Classification of Groups :-

Dwight Sanderson suggested a three fold classification of social groups. He classified them into involuntary, voluntary and delegate groups. Tonnis classified groups in communities and associations’ .Cooley classified groups on the basis of kind of contact into primary and secondary groups. In a primary group there is a face to face and intimate relationship such the family. In Secondary group relationships are indirect, secondary or impersonal such as political party.

F.H. Giddings classified groups into genetic and congregate. The group genetic group is the family in which a man born involuntarily. The congregate group is the voluntary group into which he moves or which he joins voluntarily. George Hasen classifies groups on the basis of their relations to other groups into unsocial, psedo-social, antisocial or pro-social. Meller divided social groups into horizontal and vertical groups. Charles A Ellwood distinguished among involuntary and voluntary, Institutional and non institutional, temporary and permanent group.

Summer made distinction between an in-group and out-group. The groups with which the individual identifies himself are his in-groups such as family, friend’s religion etc. An out-group consists of those persons, whether formally organized or not, towards whom we feel the sense of indifference, avoidance, disgust, competition or outright conflict. The distinction between in-group and out-group is usually expressed in the contrast between “they” and “we” for example we are democrats they are communists. Such attitude that these are my people’ and ‘those are not my people’ produce a sense of attachment to the other members of in-group while a sense of indifference with the members of out group.

Cooley’s Classification

Primary Group-
A Primary group is a small group in which a small number of persons come into direct contact with one another. They meet face to face for mutual help, companionship and discuss on common questions. They live in the presence and thought about one another.

Secondary Group-
A secondary group is one which is large in size such as a city, nation or political party. Here, human contacts become superficial and undefined. The relationship of the members are limited in scope and arrived at by much trial and error and in terms of self interest calculations of the members.

Reference groups –
Man is an imitative animal.The desire to imitate others individuals is instinctive in him.when one finds another person progressing in life, he also desire to progress like him. He compares himself with other and begins behaving like them in order to reach their status and positions. Such behaviour after comparisons with other is called reference be haviour. The concept of social reference group behaviour was given by Hayman later, Turner, Merton and Sheriff further elaborated this concept.