Why is an overview of a movie called a 'movie trailer'?

Originally these short ads for upsoming films would be shown after the main film (before the main film they showed news films) therefor they trailed after the main film. http://en.wikipedia.org/wiki/Movie_trailer Trailer (film) From Wikipedia, the free encyclopedia (Redirected from Movie trailer) Jump to: navigation, search Film trailers are film advertisements. They are shown before the screening of another movie, at a cinema where the films will be exhibited, and in the lobby, and on Internet. They are more formally known in theaters as previews of coming attractions. The term "trailer" comes from their having originally been shown at the end of a film programme. Although that practice did not last long, due to patrons tending to leave the theater after the films proper were finished, the name has stuck. Trailers have since been shown before the film begins (or before the first film (a-film) in a double-bill programme begins). Trailers normally consist of a series of selected shots from the film being advertised. Since the purpose of the trailer is to attract an audience to the film being advertised, they usually draw from the most exciting, funny, or otherwise noteworthy parts of the film but in abbreviated form and without producing spoilers. The scenes are not necessarily in the order in which they appear in the film. This helps avoiding spoilers. Some trailers use "special shoot" footage, which is material that has been created specifically for advertising purposes and which does not appear in the actual film. One of the most notable films to use this technique was Terminator 2: Judgment Day, whose trailer featured elaborate special effects scenes that were never intended to be in the film itself. Another one of the most famous "special shoot" trailers was that used for the 1960s thriller Psycho which featured director Alfred Hitchcock giving viewers a guided tour of the Bates Motel, eventually arriving at the infamous shower. At this point, the soft-spoken Hitchcock suddenly throws the shower curtain back to reveal the only scene from the movie included in the trailer