In a theatrical adaptation, material from another artistic medium, such as a novel or a film is re-written according to the needs and requirements of the theatre and turned into a play or musical.
Directors must make artistic decisions about what to include and exclude from the source material.
The original mediums have a significant influence on these decisions, for example, much must be elided in the adaptation from a novel to a stage production, due to practical time constraints.
[1] The Lion King was originally a 1994 Disney animated film and its theatrical adaptation has become the most successful musical in history.
The 1975 musical Chicago was adapted from a 1926 play by Maurine Dallas Watkins, who was a reporter and used her experiences with real-life criminals to form the basis of the story.