The Mafia is a secret criminal organization that has great economic and political control over large parts of Sicilian society and operates both criminal and legitimate enterprises in the United States. It is believed to have started during Sicily's late Middle Ages, beginning as separate bonds of strong-arm enforcers hired by local landowners. It eventually evolved into a network of independent groups governing in rural areas. With the Sicilian immigration of the late 19th century, the Mafia began to operate in several large United States cities. During the period of Prohibition it monopolized the trade in bootleg liquor and controlled loan sharking, gambling, and prostitution. Competing Mafia families established mutually recognized territories, reaching agreement by negotiation or by intimidation. By the mid-1930 the Mafia had taken on the institutionalized structure that is now typical of organized crime in the United States. Sammy the Bull, lesser known as the infamous Salvatore Gravano, is the highest-ranking member of the Mafia ever to break his blood vow of silence and turn against his boss, Mafia giant John Gotti. In 1992, Gravano realized he was about to take the fall for Gotti, so he became a federal witness. His testimony eventually led to convictions of dozens of key Cosa Nostra figures, including Gotti, who is now serving a life sentence without parole. Sammy the Bull is now living a new life under a new name; aware he could be murdered at any moment for what he had done. He still harbors bad feelings for his former associates in the Mafia for what he considers the corruption and betrayal of what he once believed to be a brotherhood of honor. In "Underboss," by Peter Maas, Gravano tells the story of his life as a gangster and opens up the secret inner secrets of Cosa Nostra, and underworld of power, betrayal, deception, and greed. There was always the incredible possibility of violent death if you m...