Why does someone join a gang?

There are many reasons why someone may join a gang: they had a horrible childhood, they want to feel like someone cares about them and supports them, they want to be someone, it's the only way to survive on the streets, etc.

What is the initiation process like?

It is very rigorous.  Through this initiation process, one must prove their loyalty and strength.  Some aspects of the process include having the person do something to one of the opposing gangs, performing some kind of deviant act, and/or enduring a physical beating from the gang.

What kind of activities are there?

Some activities that gangs have are playing sports, partying, drinking, graffiting, etc.

What is the significance of tattoos and other symbols?

Things such as tattoos, colors, way of dress, lingo, and hand gestures are all ways that a gang distinguishes themselves from other gangs.  It can also represent stories or aspects of the gang's history.  For example, some gangs may tattoo tear drops for each person that they have killed while in the gang.  If someone has symbols that are different from theirs, they know that they are an opposing gang, which may lead to violence and other severe acts.