Gangs
Gangs are a criminal organization. There are large and smaller gangs. Gangs often have a territory or turf that they protect.
Gangs are always watching their turf and try to keep other gangs out of it. Gangs often identify themselves with certain types of clothes, jewelry, tattoos, hand signs, colors, or even words. They also often have a street name for each of the gang members.
Once you join a gang it can be nearly impossible to leave. Gang leaders might threaten their families it they attempt to leave.