Tattoos have always been used as a means to identify members with particular gangs. Members use tattoos for several reasons. Some members will have numerous tattoos, particularly if they have spent time in prison. These tattoos may include one or more symbols that has been adopted as something unique to identify it’s members.
Tattoos such as a tear drop under an eye or a spider web represent prison time. Many members will have their name tattooed in large bold letters so that rival members will be intimidated. For the uninitiated wearing an unauthorized tattoo could be very dangerous particularly in prison. Prison inmates have been known to remove unauthorized tattoos from non members by literally cutting the tattoo off the person’s flesh.
Some members in particular take pride in branding themselves as outside of the boundaries of conventional society. Tattoos are also used to express their often nihilistic philosophy. Gangsta style tattoos popularized by rappers are often done in a black and gray style and depict firearms, bullets, secret letters and numbers, in old English or gothic script. It is common to have the name of the person tattooed on the back of the neck or have a motto tattooed on the chest.
It is clear that tattoos have been adopted by mainstream society even though not too many middle-class wannabes are willing to get facial tattoos, or tattoos on their hands - practices common amongst members.
But although gang members try to use tattoos to separate themselves from mainstream society, the effect it has had on the young hip middle class is undeniable. Teenagers who may have no idea of these symbols' original meaning are now wearing tattoos which were originally worn by gang members as badges of honor.
There are many prison gangs in California, the two main ones are:
The Sureños which is Spanish for Southerners. They are a group of hundreds of Hispanic street gangs with origins in Southern California. They are connected with the Mexican Mafia prison organization. The Sureños were the first California gang to make use of gang colors to distinguish themselves from other gangs.
The state of California prison system provided railroad handkerchiefs to inmates in one standard color: blue. Hispanic inmates from Southern California selected or claimed the blue bandanas to identify themselves. Once a member of the Sureños graduates off the street and into the prison system they are designated a part of the Mexican Mafia organization.
Source : http://www.tao-of-tattoos.com/gangs.html