The document defines groups and their key characteristics such as interaction among members, common interests or goals, and members seeing themselves as part of the group. It discusses different types of groups including formal groups established by an organization, informal groups, and change membership groups. The types and purposes of formal and informal groups are described. Factors influencing why people join groups and the benefits of groups from an organizational perspective are also summarized. Stages of group development including forming, storming, norming, performing, and adjourning are outlined. Alternative theories of group development and some limitations of groups are mentioned. Key aspects related to group norms, tasks, cohesiveness, and increasing/decreasing cohesiveness are defined at a high level