The term "underworld" refers to the network of criminal organizations and activities that operate outside the law. This includes various groups involved in illegal enterprises such as drug trafficking, human trafficking, and organized crime. The underworld often has its own codes of conduct and hierarchies, with leaders known as mobsters or gangsters. Criminal underworlds can vary significantly by region and culture, with notable examples including the Mafia in Italy and the Yakuza in Japan. Law enforcement agencies work to combat these organizations, but their secretive nature and extensive networks make them challenging to dismantle.