Well, the word gang technically means a group of people. If there isn't a group, than it is called a person, not a gang.
groups, mobs
Yes. Many of them are neo Nazi groups.
groups of people who shoot stuff up.
Because that's just how the world is, gangs are everywhere, they've always been here, and always will be.
Changes between groups, usually scared, this explains why they hang around in gangs. Maybe all white or all black.
groups, crowds, packs, bands, bunches, mobs
Sometimes juveniles join gangs for protection. Juveniles who go to juvi do not always join gangs fr protection.
knoe people join gangs because they want to be cool
Meerkats are the territorial type that live in groups called gangs. As with most territorial, group-based animals, their biggest competetors are other gangs of meerkats.
Actually that's a reference to massive gangs of vampires that orginated in Atlantis.
They were organized in groups of about 20 with one white comander
No real "gangs" but there will always be thugs and those that would be in a gang were it not 20 degrees below zero while hanging out at the street corner.