Short answers, pulled from the story.
Horror film is a genre that seeks to elicit physical or psychological fear in its viewers. Max Schreck as Count Orlok in the 1922 film Nosferatu set a template for the horror film, according to critic and historian Kim Newman.
The ideas and terminology of horror films did not yet exist as a codified genre before the release of Dracula (1931). Horror became a codified genre only after the release of Dracula (1931) following its origins in silent films and German Expressionism.
Lighting extremes prevent viewers from seeing every detail in a scene which provokes unease while bright lighting might trick viewers into feeling safe. Directors also use tilted camera angles and shots in slow-motion or reverse to confuse and disorient horror film viewers.
Body horror is a genre that emerged in the 1970s focusing on the process of a bodily transformation. The earliest appearance of the sub-genre was the work of director David Cronenberg specifically with early films like Shivers (1975).
Constraints on permitted subject matter in Indonesian films have influenced Indonesian horror films while China banned all horror films from its market in March 2008. Moral panics over several slasher films in the 1980s led to many of them being banned but released on videotape in the United Kingdom.