This document summarizes different types of social groups based on various classification schemes. It discusses groups classified by size, including dyads, triads, and groups of 4 or 5 people. Groups are also classified by their structure as formal groups, which have rules and regulations, and informal groups, which do not. Formal groups include voluntary, coercive, and utilitarian groups. Social groups are also classified based on the nature of social ties as primary groups with close personal ties and secondary groups with more impersonal ties. Finally, groups are classified based on social relations as un-social, pseudo-social, anti-social, or pro-social groups, and based on identification as in-groups, out-groups, or