Various companies, including Internet Service Providers, form networks in a given region of the country. These are known as regional networks (also called "midlevel networks") and may be provided by for-profit entities such as PSINet or UUNet, or by universities or consortia of universities, such as “SURANet,” the “SoUtheastern Regional Area Network.” There are over 20 regional networks in the United States.
A "regional network" with no further connections to other networks could only provide services such as e-mail and Web browsing directly within its own area. Regional networks therefore contract with a backbone network to be connected to, and thereby have access to, any place on the Internet that that backbone network reaches. This is the means by which the backbone companies earn revenue from the installation of the backbone.