Literary adaptation

Literary adaptation is adapting a literary source (e.g. a novel, short story, poem) to another genre or medium, such as a film, stage play, or video game.

It can also involve adapting the same literary work in the same genre or medium just for different purposes, e.g. to work with a smaller cast, in a smaller venue (or on the road), or for a different demographic group (such as adapting a story for children). Sometimes the editing of these works without the approval of the author can lead to a court case.

It also appeals because it works well as a story; it has interesting characters, who say and do interesting things. This is particularly important when adapting to a dramatic work, e.g. film, stage play, teleplay, as dramatic writing is some of the most difficult. To get an original story to function well on all the necessary dimensions—concept, character, story, dialogue, and action—is an extremely rare event performed by a rare talent.

Perhaps most importantly, especially for producers of the screen and stage, an adapted work is more bankable; it represents considerably less risk to investors, and poses the possibilities of huge financial gains. This is because:

It has already attracted a following.
It clearly works as a literary piece in appealing to a broad group of people who care.
Its title, author, characters, etc. may be a franchise in and of themselves already.