(WYTV) – Movie trailers are called “trailers” because at first, they appeared after a movie — they trailed the film.

The first known movie trailer shown in a theater was in November 1913.

The advertising manager of the Loews theaters, Nils Granlund, tacked it onto the end of a film. The trailer was for the musical “The Pleasure Seekers,” which was about to open on Broadway. So it really wasn’t a trailer for another movie, but for a live stage play. The trailer included short clips of the rehearsals.

The idea caught on and trailers began appearing routinely after films. It didn’t take long for movie studios to realize trailers could be full film advertisements and would be more effective if they showed up before the movie, instead of after when people are leaving.

By the end of the 1930s, the switch was complete.

The most common trailer format today comes in three acts — Act 1 sets up the story, Act 2 highlights the main plot and Act 3 features a powerful piece of music with a visual montage of the action or the humorous moments in the film, depending on the film type.

The Motion Picture Association sets the time limit for any movie trailer shown in theaters or on TV — two-and-a-half minutes with one exception. Each studio can exceed this time limit once per year if it feels a certain movie deserves it.

Trailers shown on the internet or on home videos have no time restrictions.