Gang

A gang is a group of people who do things together. The word "gang" comes from the Old English "gan", which means "to go". It is also related to Old Norse "gangr" "a group of men". In modern times the word "gang" is often used to refer to a group of people who commit crimes together. Members of criminal gangs may be called gangsters.
There are several reasons why people join gangs. Lots of people who join gangs are young people. One reason that people join gangs is a chance to make money through doing things like selling illegal drugs or stealing. Another reason, especially for younger people, is a chance to have a place where they belong. A third reason is boredom.
Gang identification.
Gang members often use graffiti to tell other gangs that an area is part of their "territory" and that other gangs should stay away. Graffiti is also used to send other messages. Members of a gang often dress similarly or have the same tattoos.
Gang violence.
Gang violence refers to illegal acts of violence performed by gangs. The violence may be against innocent people, property, or other gangs. Gang violence is extremely prevalent across the world in cities like Moscow, Detroit, Chicago and Los Angeles. Nearly every major city has seen gang violence at some point in its history.