The American soap opera "The Guiding Light" (retitled "Guiding Light" in 1975) started as a radio drama in January 1937 and later moved to the CBS television network in June 1952. With the exception of several years in the late 1940s, when the show's creator Irna Phillips was involved in a dispute with Procter & Gamble, "(The) Guiding Light" was heard or seen nearly every weekday since it began, until 2009 making it the longest story ever told in a broadcast medium.

Originally serials (soap operas) were broadcast as fifteen-minute installments each weekday in daytime slots. In 1956, "As the World Turns" and "The Edge of Night," both produced by Procter & Gamble Productions, debuted as the first half-hour soap operas on CBS.

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