Movie trailers are short film advertisements of new movies that are not yet in theatres. They are previews of the film that give hints of its story line and introduce the actors and the scenery.

Trailers are so named because in the early years of cinema, the advertisements for one film were shown after another film. Trailers are now shown at the beginning of movies so that people do not miss them.

Trailers are often the best shots selected from the most funny or exciting moments of the movie. Some trailers carry special footage-scenes shot only for advertisement and left out of the movie. For example, in a trailer for the classic Casablanca, the character Rick Blaine says,