Groups form when two or more individuals interact regularly, are aware of one another, and see themselves as part of the same group. People join groups for several key reasons: closeness and bonding with others, achieving common goals through collaboration, and fulfilling personal objectives like prestige and importance. Groups in the workplace include both formal groups set up by management and informal groups that emerge to meet personal needs. What makes an effective group includes cohesiveness, clearly defined roles and norms, a sense of status among members, and homogeneity. Joining a group provides benefits like increased productivity, skills development, self-knowledge, and fulfilling social and growth needs.