A trailer is basically a short advertisement for a film. Usually borrowing small pieces of the film, it can be a problem to make one, sometimes harder to make than the movie itself. A good trailer encourages people to go see the film (or to rent or buy it if it's on DVD), but at the same time shouldn't give away too much of the film, and to be honest, should not promise things that are not in the [...] [tvtropes.org]