Jail and prison populations involve people living in very close proximity to one another (in some housing situations, the toilet seat might be only a few inches from your face when you’re lying in bed), so it is natural to expect that a culture and social structure will emerge.
At the top of the heap would be high-ranking members of crime organizations. Old-style Mafia first come to mind. These guys are still powerful, but maybe not as much as they used to be.
More likely you’ll find people in what are usually called “gangs,” e.g. Crips, Bloods, Black Guerrilla Family, Latin Kings, MS-13, etc. There are also gangs that operate mainly within prisons, such as the Mexican Mafia, Aryan Brotherhood, United Blood Nation, etc. Most established prison gangs have alliances with “free world” gangs.
Members of these gangs, the “soldiers,” are the next level down. They are protected by other gang members, as an insult or assault on any gang member is viewed as an act against the entire gang. The origin of prison gangs was for mutual protection, usually against other ethnic/racial factions. Prison and street crime gangs don’t have much of an equal opportunity program.
Below this level are run-of-the-mill prisoners who have no gang alliance. This is the largest group of prisoners. They do their best to stay out of gang politics and disputes. Barring some complications where one runs afoul of a gang member, it’s easily possible for an inmate to quietly do their time. Prison etiquette must be observed, e.g. don’t disrespect others, don’t help the staff with investigations, remain in your own area, etc., but most will not be pressured to join a gang.
Some prisoners are called out for their lack of confidence and backbone, and made “wives” of other inmates. Some of their duties are housekeeping and other menial chores, and some are sexual in nature. Assuming this role means you have a protector, so you’re safe from other inmates (as long as your “owner” remains powerful, anyway), but you’re essentially the slave of the inmate who co-opts you. This happens, but not as often as prison movies might have you believe.
Below this are inmates who are incarcerated for crimes even other inmates find reprehensible. Crimes where the victims could be another inmate’s loved ones are targeted.
These include rape and sexual offenses against children. Inmates will victimize these people just to act out rage gathered from other sources, because they have no relevant social status. They are throw-away people.
Ironically, these inmates can be the easiest ones for the staff to manage. They are often more intelligent and well-educated than the average inmate, and they don’t want to make enemies among the staff. They might get prison jobs where their intellect is useful, like clerking or assisting with educational programs.
At the bottom of the stack, lower than low, are informants, or “snitches.” You don’t have to participate in another inmate’s rule-breaking or crime, but you never tell staff what another inmate is up to. Doing so often means a semi-permanent assignment to administrative segregation, where you spend most of your time in your cell and have few privileges or diversions. Even if the inmate you informed on is released, goes to another institution, or dies, he likely still has friends on the inside who will waste no time in reminding you that you violated the inmate code of conduct.
– Tim Dees