Prequel is a term in drama and literature: it means the opposite of sequel. When a story is told in several stages, it is natural to tell it in order of time. For example, a series of books on the Second World War started with the 1930s, and ended up in 1946.
For various reasons, this does not always happen. In the movie series Star Wars, the first movie was Star Wars Episode IV: A New Hope (1977). It was followed by three prequels, which were Star Wars Episode I: The Phantom Menace (1999); Star Wars Episode II: Attack of the Clones (2002) and Star Wars Episode III: Revenge of the Sith (2005).
For correct use, the term 'prequel' is only applied when work is part of a series, and when the later publication refers to an earlier time. It is an old idea, but one which is often used today for drama on movie and television. The Cypria, a work of Ancient Greek literature, is a prequel to Homer's Iliad. A related idea is the back-story, which is the background story of a main story or character.
- Churchill, Winston S. 1948–1953. The Second World War. 6 vols, Macmillan, London.