A gang is, by definition, a conflict group at war with other groups or with the forces of organized society. It may originally have formed spontaneously, but it is integrated through conflict. Boy-groups or gangs in many cities are an important factor in juvenile delinquency, in the beginnings of criminal careers, in organized crime, and in political corruption.
In the UK in 1988, 3% of male murders and 1% of female murders were attributed to gang warfare. During 3 months in 1991, 270 gang members in Los Angeles were killed.
The result of collective gang behaviour is the development of tradition, unreflective internal structure, [esprit de corps], solidarity, morale, group awareness, and attachment to a local territory.