In the United States, commercial radio stations generate most of their revenue by selling airtime for radio advertisements. These advertisements are paid for by a business or service in exchange for the station airing their commercial or mentioning them on air. The most common type of advertisement is the "spot commercial", which typically lasts no longer than one minute. Longer advertisements, often running for 45, 60, or more minutes, are known as "infomercials" and provide more detailed information about the promoted product or service.
The United States Federal Communications Commission (FCC), established under the Communications Act of 1934, regulates commercial broadcasting. Many of the relevant laws have remained relatively unchanged since the Radio Act of 1927. In 2015, radio accounted for 7.8% of total U.S. media expenditures.