Trailers are short previews of films used to advertise upcoming releases. They are designed to give the target audience an idea of what the film is like and help them decide if they want to see it. Trailers showcase the best or most exciting clips and aim to generate interest in the film's unique selling point. They are distributed through cinema screenings, television broadcasts, and online platforms like YouTube to reach the intended demographic. Teaser trailers are released early to build hype leading up to the film's full trailer and eventual release.