The term "book-to-movie adaptation" refers to a film that is based on or derived from an existing book. This means that the storyline, characters and events in the movie are adapted from those found in the written work. The process involves selecting a novel, autobiography, short story or nonfiction book as source material for a screenplay, which is then developed into a script for a film. Many popular movies today have been adapted from books, such as "The Hunger Games," "Harry Potter" and "Twilight."