Trailer music is the backgroun music used for film previews, which is not always from the film's soundtrack. Often, people will notice the movie previews they see in theaters will feature music that is dramatic, soothing, or whatever kind of sound complements the movie clip scene. Since the score for a movie is usually composed after the film is finished (which is much after trailers are released), a trailer will sometimes use music from other successful films as a subconscious tie-in method.