A trailer is a series of extracts that depict the plot outline of a film without revealing too much to the audience and intrigues them into watching the film. The extracts tend to be of the most exciting or funny moments within the space of around 2 minutes and 30 seconds, which is the maximum length set by the Motion Picture Association of America (MPAA). There are two types of trailer in particular: teaser trailers and theatrical trailers.
Teaser Trailer
Teaser trailers are usually released long in advance of a product in order to "tease" the audience. These also usually help create "hype" over a film, especially in the case of films in a series, such as Star Wars.
Teaser trailers tend to be around 1 and a half minutes long due to the fact that these are released early in production and therefore the producers do not have all the footage they need yet. It also creates mystery as it does not reveal the plot yet, leaving the audience in suspense. These teaser trailers are more common with big budget films that want to build up their audience to be large. An early example of a teaser trailer is the 1978 trailer for the Superman film directed by Richard Donner.
Theatrical Trailer
Released closer to the end of production/in the products final stages, the theatrical trailer tends to be around 2 and a half minutes long and contains more footage that reveals a rough outline of the plot without spoiling the film. It is heavily edited and often contains voice overs and title credits that inform the audience.
