Teaser Trailers.

When production companies are marketing a film they want it to get as much exposure as it can. One of the ways they try and do this is by releasing trailers in the run up to the films release. These trailers can be released as early as a year before, however, the closer to the films release the more in-depth the trailers are and will give away more information on the plot. 

Teaser trailers are usually around 30 seconds long, fast pace and don't reveal too much about the characters in the film or the plot. A teaser trailer for an action film will most likely be used to show off some of the special affects as that is a big selling point, similarly a comedy teaser trailer will feature some of the best jokes from the film. 







Full length trailers, which are released closer to when the film is, are not ply longer than teaser trailers but show more of the plot and how the characters fit into it.