At one time, the radio was the sole electronic medium of general relevance. Its programs fulfilled the function of providing non-stop entertainment and information. The challenge posed by television has caused it to specialize; today its users look to it a) to provide certain service functions, and b) to accompany them when they are out and about. With examples from the history of radio in various countries up to the present, the author delineates the specifics of radio communication, concentrating on subject matter, the expressive means employed, text varieties and formats.