A teaser trailer is a short version of a movie trailer that is designed to pique the interest of the audience, getting potential viewers excited about an upcoming film. Teasers, as they are called, are typically released months in advance, sometimes as much as 18 months before the expected release date of the film, and they are used to build anticipation and curiosity about the films they advertise. These trailers can be seen before feature films in some movie theaters, and they are also released online and shown on television.
Classically, a teaser trailer lasts between half a minute and a minute. It may include footage from the film, often in a rough stage since the film has not been completed, or it may use entirely new source material. In some cases, a teaser is simply an abridged version of a regular movie trailer, including the film's tagline and key footage in a condensed version that is more television-friendly.
Some companies like to make trailers that literally tease their audiences with puzzles and cryptic references. For example, one might flash a few key images, followed by a title card with the date. Viewers are supposed to recognize the images, and understand that the date is the projected release date. This works best for iconic films and films in a series, as viewers become familiar with specific symbols. A classic example of this type would be a promotion of a Batman film that flashed the famous bat symbol on the screen, followed by a date.
Teaser trailers may also include hints and clues that viewers can follow, if they feel so inclined. It is becoming increasingly popular to include web addresses in trailers, so that viewers can go look up the film online, and some movies had used these addresses as a jumping-off point to involve viewers in an alternate reality game or series of puzzles, thereby drawing them into the story of the film. Others offer viewers the opportunity to sign up on a mailing list for news about the film, including notifications when longer movie trailers are released.
From a marketing perspective, the teaser is a brilliant tool. The brief advertisement is usually not terribly costly to make or expensive to air on television, and it can suck viewers in, getting people hyped up about a movie months before it is released. These trailers are often used to promote big budget films, with the goal of getting a return on the investment as quickly as possible, and they are also used to increase fan interest in major series or eagerly-awaited film adaptations of books or continuations of television shows.