The document discusses how genre is identified semantically and syntactically in films and trailers. Syntactically, horror films follow predictable patterns of events such as introducing the protagonists, deaths occurring to create conflict, and the antagonist being defeated. Semantically, elements like dark locations, lighting, sounds, and music are used to create tension and signify danger. The trailer for "I Know What You Did Last Summer" follows some but not all of the usual syntactic events and does not reveal the antagonist or ending to avoid spoilers.