Most gangs today are either turf-oriented or profit-oriented. Turf-oriented gangs are traditional in nature. The heritage of its members can be traced back for generations, and these gangs lay claim to an area, usually the area surrounding their neighborhood, as "their territory." Profit-oriented gangs operate primarily to make money and are nontraditional. They tend to be mobile, moving from area to area in attempts to expand their business ventures. The typical street gang is still loose-knit in structure. Less than 10 percent of a gang's membership is hardcore (deeply committed). Most who claim membership are somewhat involved in the gang's daily activities. Associate members are friends, acquaintances, and relatives of active members. The language of the gang subculture consists of street-slang terminology. Basic rules of grammar do not apply. Nonverbal forms of communication include graffiti, clothing, hand signs, and tattoos. Research through the U.S. Office of Juvenile Justice and Delinquency Prevention has shown that gang homicides are "characterized by periodic spurts and declines, they have been increasing nationwide and evidence an overall growth trend in certain cities." The use of firearms has contributed significantly to the homicide rate. Internally, violence strengthens the bond between gang members. Externally, gangs use violence to protect their turf or business operations, to expand their territory, to defend their honor, and to control their neighborhoods. Studies have shown that although a youth who belongs to a street gang has a higher propensity to use drugs and that a fair portion of those who belong to gangs sell drugs locally, the typical street gang lacks the necessary organizational structure required to succeed in the drug-trafficking business.