Statistics published by the National Fire Protection Association indicate that arson fires are heavily concentrated in structures, costing about $4-6 billion annually. Residential fires account for between 45-50 percent of the structures burned. Persons involved in arson fires are typically organized crime (associated with loan sharking, extortion, and to cover another crime); individual building owners desiring to profit from the burning of their own buildings or residences; business persons who set fires to cover the cost of modernization, loss, or inventory depletion; and persons whose firesetting stems from emotional instability. Arsonists commonly use flammable and combustible liquids to start fires; however, some use paper, rubbish, and other solid combustible materials so as to cast less suspicion that a fire was arson. Timing devices are preferred by arsonists because this affords them the opportunity to be away from the scene when the fire starts. A popular method is to place gasoline in a light plastic container and then apply a timed heat source to the plastic so that it melts and releases gasoline vapor, which will generally ignite. Juvenile firesetters may set fires in the home either out of curiosity about the effects of fire or to express hostility against parental control. One table and references are provided.