A trailer is a short video advertisement that provides sneak peaks of an upcoming film to generate interest. Trailers aim to show the best parts of the film in 2-3 minutes to entice audiences to see the full movie. Trailers follow a narrative theory called the "equilibrium theory" where there is initially a balance that is disrupted, characters recognize the disturbance, and try to fix it (though trailers do not show the actual resolution). Company logos and identifiable titles are included to establish the producers and genre. Music and sounds are carefully selected to set the mood and build tension, often changing when something unexpected occurs. The goal is to attract audiences and create intrigue around the story without revealing the entire plot.