The news media of the United States consist of several different types of communications media: television, radio, newspapers, magazines, and Internet-based Web sites. Many of the media are controlled by large for-profit corporations who reap revenue from advertising, subscriptions, and sale of copyrighted material. Some people allege that the success of such companies may be due to certain policies of the American federal government, though it may be just as likely that the media field is prone to natural monopolies.