Sum up of teaser trailers

None of these 3 trailers give away the main story of the film, the part that makes the film most exciting, or evokes the most emotion.
The Dark Knight's trailer had no visual, but was all dialogue based, so that was all that viewers could rely on to find out about the film, whereas Inception's trailer was the opposite way round; all visual but no dialogue. Toy Story 3 had all of it combined, but the trailer was separately made and had no clips from the actual film. From these teaser trailers you learn a little bit about the main characters and the roles they play in the film, and you can also understand the genre from the small bit of information your given.

From analysing these three teaser trailers I have learnt that the teaser is all a dramatic hype for viewers, and always leaves you wanting to know more about the film. They usually start out slow, and the pace speeds up until you get to the most dramatic part of the trailer where all the shots move quicker, the soundtrack/dialogue gets more intense and the visual (if any) is more dramatic.