Gangster is a term that is usually used to describe people who are members of organized criminal organizations. These individuals generally operate in a structured way, and they may have a specific job within the criminal organization. Some gangsters are considered violent, while others may be more involved in the financial areas of organized crime. It is generally common for gang cultures to spring up in the poorer segments of a given population.
Anytime there is some kind of legal prohibition of something that people have come to expect, organized crime will usually come in and try to sell the forbidden service or substance on the black market. For example, in the 1920s in the United States, alcohol was prohibited, and the gangster culture at the time thrived by selling liquor to people for high prices. Other examples of this kind of business strategy include selling illegal drugs along with prostitution and gambling services.
Sometimes organized crime organizations have very strict rules about recruiting new gangsters, and often the groups are based around ethnic or geographical separations. In some cases, there may be complex rituals or hazing procedures that new members have to endure. Many gangster groups can also have very strict rules about maintaining secrecy among the members. If members break these rules or reveal information to government authorities, there can sometimes be violent punishments.
One common problem is that gangsters from one group may fight with gangsters from other groups over turf or customers. In the legitimate business world, competition can be tough, but everybody is generally bound by certain rules. When gangster groups start competing with each other, these rules are sometimes thrown aside, and violence is a common result. In order to avoid these kinds of problems, rival gangs may have certain agreements establishing boundaries and areas where each group of gangsters can operate without fear of retribution.
Sometimes organized criminal groups will operate within legal boundaries by using legitimate businesses, and these may help cover for the illegal activities going on in the background. One example of this kind of situation would be if an organization opened up a Laundromat™ and operated an illegal gambling business out of the back room. In a situation like this, the laundry business may be profitable on its own, but the main money would usually come from the gambling.