Η δασκάλα με τα ξανθά μαλλιά 1969

Trailers or previews are advertisements for films that will be shown in 1 to 3 months at a cinema. Back in the early days of cinema, with theaters that had only 1 or 2 screens, only certain trailers were shown for the films that were going to be shown there. Later, when theaters added more screens or new theaters were built with a lot of screens, all different trailers were shown even if they weren't going to play that film in that theater. Movie studios realized, that the more trailers that were shown (even if it wasn't going to be shown in that particular theater) the more patrons would go to a different theater to see the film when it came out. The term "trailer" comes from their having originally been shown at the end of a film program. That practice did not last long, because patrons tended to leave the theater after the films ended, but the name has stuck. Trailers are now shown before the film (or the A movie in a double feature program) begins.

Movie trailers are now also common on DVDs and Blu-ray Discs, as well as on the Internet and mobile devices. Of some ten billion videos watched online annually, film trailers rank third, after news and user-created video.[12]

Teasers are a much shorter preview that would last only 10 to 30 seconds. Teasers were used to get patrons excited about a movie coming out about 6 to 12 months away.