This document discusses social groups and organizations. It defines social groups as families, friends circles, clubs, religious congregations and more. Groups are described as either formal or informal based on their structure and nature of interaction. Key characteristics of groups include regular interaction and communication among members. The document goes on to classify groups into primary and secondary groups, comparing their characteristics such as size, relationship intimacy, decision-making processes and more. It provides examples like families for primary groups and work colleagues for secondary groups. Influential sociologists who studied groups, such as Joseph Fichter, Charles Horton Cooley and William Graham Sumner, are also cited. Finally, the importance of groups for providing solidarity and cohesion is