What kinds of groups are informal?

Families, cliques, friendship groups, neighbors, lovers, gangs, close work colleagues, bowling buddies, best friends, the Friday poker group, the weekly four-some golfers, a village clan, extended family members, a cult or terrorist group, the local mob….

Families, cliques, friendship groups, neighbors, lovers, gangs, close work colleagues, bowling buddies, best friends, the Friday poker group, the weekly four-some golfers, a village clan, extended family members, a cult or terrorist group, the local mob….