A short montage of the film’s key moments, revealing the basic informations of the film (genre, story, actors, producers etc.) in 10-30 seconds. Its goal is to convince the audience to go to see the entire production by showing dramatic, provocative, intriguing, funny scenes from the movie.
In marketing communication teaser is a forerunner of an advertising campaign to arouse the curiosity and the attention of the consumer.

Owens, Jim & Millerson Gerald (2012). Television production. Taylor & Francis. Oxford. p. 419.
Business Dictionary retrieved 31.10. 2014