Radio drama (or audio drama, audio play, radio play, radio theater) is a dramatized, purely acoustic performance, broadcast on radio or published on audio media, such as tape or CD. With no visual component, radio drama depends on dialogue, music and sound effects to help the listener imagine the characters and story: “It is auditory in the physical dimension but equally powerful as a visual force in the psychological dimension.”
Radio drama achieved widespread popularity within a decade of its initial development in the 1920s. By the 1940s, it was a leading international popular entertainment. With the advent of television in the 1950s, however, radio drama lost some of its popularity, and in some countries has never regained large audiences. However, recordings of OTR (old-time radio) survive today in the audio archives of collectors and museums, as well as several online sites such as Internet Archive.
As of 2011, radio drama has a minimal presence on terrestrial radio in the United States. Much of American radio drama is restricted to rebroadcasts or podcasts of programs from previous decades. However, other nations still have thriving traditions of radio drama. In the United Kingdom, for example, the BBC produces and broadcasts hundreds of new radio plays each year on Radio 3, Radio 4, and Radio 4 Extra. Podcasting has also offered the means of creating new radio dramas, in addition to the distribution of vintage programs.
The terms "audio drama" or "audio theatre" are sometimes used synonymously with "radio drama" with one possible distinction: audio drama or audio theatre may not necessarily be intended specifically for broadcast on radio. Audio drama, whether newly produced or OTR classics, can be found on CDs, cassette tapes, podcasts, webcasts and conventional broadcast radio.
Thanks to advances in digital recording and Internet distribution, radio drama is experiencing a revival.