This document provides an overview of groups and social groups. It defines a group as consisting of two or more people engaged in some relationship with each other. Membership in groups can be through assignment such as family or achievement such as joining a club. Characteristics of social groups include interaction among members, cohesiveness, morale, interdependence, and identification with the group. There are different types of groups that vary in size, roles, and communication patterns. The presence of others can both positively and negatively impact individual performance depending on the complexity of the task. Social loafing is when motivation and effort decrease when working collectively compared to individually.