The process of making a work of art upon the basis of elements provided by an earlier work in a different, usually literary, medium; also the secondary work thus produced. Literary works have been adapted in many forms: fairy tales as ballets, plays as operas, novels as stage plays (see dramatization), stage plays as novels or short stories. Since the early 20th century, new entertainment media have encouraged the adaptation of plays and novels as films or as radio (and later, television) dramas, and conversely the ‘novelization’ of film or television screenplays into books. Distinctions are commonly drawn between ‘faithful’ adaptations, in which the distinctive elements (characters, settings, plot events, dialogue) of the original work are preserved as far as the new medium allows, and ‘free’ adaptations, sometimes called ‘versions’ or ‘interpretations’, in which significant elements of the original work are omitted or replaced by wholly new material. For an introductory survey, consult Julie Sanders, Adaptation and Appropriation (2005).