<human>:  Why is the genre of dark fantasy called dark fantasy?
<bot>: Dark fantasy is a subgenre of fantasy. It is a subgenre because it is a subset of a genre. A genre is a set of things that share common features. In the case of fantasy, the common features are magic and mythical creatures. Dark fantasy is a subset of fantasy because it focuses on stories about characters who are not necessarily good or bad, but who have a darker side. The darkness of the fantasy is usually in the form of supernatural elements such as magic or monsters.