Trailers tell the story of a film in a highly condensed fashion to have maximum appeal. In the decades since film marketing has become a large industry, trailers have become highly polished pieces of advertising, able to present even poor movies in an attractive light. Some of the elements common to many trailers are listed below.

Trailers 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, these excerpts are usually drawn from the most exciting, funny, or otherwise noteworthy parts of the film but in abbreviated form and usually without producing spoilers. For this purpose the scenes are not necessarily in the order in which they appear in the film. A trailer has to achieve that in less than 2 minutes and 30 seconds, the maximum length allowed by the MPA. Each studio or distributor is allowed to exceed this time limit once a year, if they feel it is necessary for a particular film.