The document discusses the main codes and conventions used in film trailers. It explains that trailers are meant to market films and raise audience expectations to encourage viewership. Key elements of trailers include displaying the film title and genre, introducing characters, using taglines and dialogue to hint at the narrative, incorporating recognizable music and sounds, and strategically editing clips to tease the plot without revealing too much. The purpose is to attract audiences and make the film seem worthwhile through these cinematic techniques.