The document discusses the purpose and conventions of radio trailers. Radio trailers are used to advertise and promote films, provide audiences with information and a summary about the film, and create awareness of the film's release date. Effective radio trailers make use of film extracts, sound effects, music and voiceovers to convey the genre and sell audiences on the film. The voiceover is especially important as it replaces visuals, and should have the correct tone and address the intended audience for the genre of film being promoted.