Generally, most people pay for Internet access, but there are companies that want that to change. These companies are trying to offer Internet access to the public for free. When users sign up, they agree to allow advertisements to be displayed on their computers. If a user turns off the advertising, then they are disconnected from the service.
Advertisers pay the companies for their ads to be displayed to users.
In the U.S. there are currently two major companies offering free Internet access . NetZero and Tritium depend on large numbers of subscribers to survive. The reason that they are prospering in the U.K. is because there are no flat rate local calls there. Users have to pay per minute for phone calls, and users are trying to avoid further costs of Internet access. In the U.S., most of the local access areas for the free ISP's are major cities.