HISTORY: The invention of radio created a technology that seemed like science fiction at the time but soon produced a booming industry.
INDUSTRY: The radio business developed around local stations, groups, networks, syndicates, and National Public Radio, a network for noncommercial stations.
CONTROVERSIES: Radio controversies revolve around the phrase "public interest, convenience, and necessity," and include the concentration of ownership, the quality of programming, and censorship.
