When we think of gangs, we see minorities hanging on broken down streets covered in grafitti and shattered glass bottles. This image is a difficult one to shake if you've ever lived near or in a town or city that is populated with gang members.
The city I grew up next to is known for it's gang activity. My family won't set foot in that town unless we have a very good reason because the likelihood of you being robbed or shot it is rather high. So before you little racist-flag toting loonies come in here, know that this is the solitary reason I don't go to this city.
Gangs represent a major problem, the lack of attention and community in places that need it the most (inner-cities, poor towns). I believe gangs come into being when a group of people feel that they've been so far oppressed that they need to start doing things by themselves for only themselves. This is evident in gang wars because people still kill each other over "turf" which has to be one of the most idiotic things I've ever heard of.
Unfortunately, I wanted to add more, but I must depart for a bit. I'll come back to this thread later, but feel free to disagree, agree, or elaborate your own points.