Approximately 1.4 million people in the United States were part of gangs as of 2011, and more than 33,000 gangs were active in the country. These include national street gangs, local street gangs, prison gangs, outlaw motorcycle clubs, and ethnic and organized crime gangs.

A gang is a group or society of associates, friends, or members of a family with a defined leadership and internal organization that identifies with or claims control over territory in a community and engages, either individually or collectively, in illegal, and possibly violent, behavior, with such behavior often constituting a form of organized crime.