Show bibles can come in different forms. Some are updated as a series progresses, and are expanded with information on the characters after the information has been established on screen, and often go into extensive detail about the character's histories. The Frasier show bible, for example, was "scrupulously maintained", and anything established on air — "the name of Frasier's mother, Niles' favorite professor, Martin's favorite bar...even a list of Maris' [dozens of] food allergies" — was reflected in the bible. The bible then serves as a resource for writers to keep everything with the series consistent.
Others are used as sales documents to pitch a new series to a television network or television studio and help them, as well as any new writers who might join the writing staff, understand the series. These types of bibles discuss the histories of the main characters as well as the fictional universe the series is set in and include a mention of future plotlines in the form of a brief outline of each season.
Bibles produced for science fiction series go into great detail describing the capabilities and limits of technology used on the show. For example, the series bible for the 2004 version of Battlestar Galactica includes detailed explanations on how the ship itself works.