A group exists when two or more people define themselves as members of it and when its existence is recognized by at least one other. (Rupert Brown 1988). The group is a set of individuals who accept the common task and who are interdependent in their execution to promote its accomplishment through interaction with each other. On the other hand, group behavior originates from the foundations that contribute to group effectiveness. Other groups interconnect with the group function, they expand their own exclusive set of uniqueness, they also develop a group structure in which they have cohesion, role, norms and processes. The group can participate with other groups when groups work together, and competition between groups also creates conflict. Group behavior was the subject of considerable study in the mid-20th century (Alford, 1994; Brown, 2001; Hogg, 2000). We describe group development and find that group dynamics consist of a set of techniques related to the internal nature of the group. Important goals and development events early in the group's life are very helpful. The group size should be between 5 and 7 members who constitute the best elements of small and large groups. The stages of group development are formation, storming, standardization and performance. Training is the first step when we try to build the group, which is characterized by a lot of improbability. The initial goal is often simply awareness, new group members are usually polite, kind and reserved. The group members naturally remain their true personal emotion. Group members try to decide what behavior is appropriate throughout group activities. On the other hand, great ambiguity exists regarding the purpose of the group, avoiding insurmountable differences. Group behavior is most effective when it has clear and strong norms that regulate behavior and ensure that coordination must be implemented. It is very important that these bulbs encourage group members to act proactively and learn from their experiences. ReferenceBrown, Rupert (1999) Group processes: dynamics within and between groups 2e. Oxford: Wiley Blackwell. Johnson, David W. and Frank P. Johnson (2003) Uniting. Group theory and group skills 8th grade. Boston: Allyn and Bacon. Alford, C.F. (1994) Group processes and political theory. Yale University Press, New Haven. Brown, R. (2001) Group processes: dynamics with and between groups. 2nd ed. Blackwell Publishing, London. Hogg, M. (2000) Blackwell Handbook of Social Psychology: Group Processes. Blackwell Publishing, London.