According to the acclaimed author, there are three levels of horror: The Gross-Out, Horror, and Terror. It is these elements that allow the genre to be diversely shocking and hypnotizing in not only literature but in cinema as well.
The distinction between terror and horror was first characterized by the Gothic writer Ann Radcliffe (1764 1823), horror being more related to being shocked or scared (being horrified) at an awful realization or a deeply unpleasant occurrence, while terror is more related to being anxious or fearful.