Ravenloft is a Gothic horror setting. Ravenloft was linked to the Forgotten Realms by way of the Ethereal Plane, and several crossovers between the two settings have officially been noted.
Ravenloft is an alternate time-space or demiplane (artificial creation), called the Demiplane of Dread, which consists of a collection of land pieces - "domains", brought together by a mysterious force known only as the Dark Powers. Each domain is mystically ruled by a "Darklord" - a person or monster who has committed an act or acts of evil so foul as to attract special attention from the Dark Powers. Within their domains, the darklords are forever tormented by the objects of their desire (often the objects they committed their crimes to achieve), which the Dark Powers dangle before them. Strahd von Zarovich, a vampire, became the first Darklord, both ruler and prisoner of his own personal domain of Barovia.
The Vistani are a nomadic ethnic group of fortune-tellers that have some control over the Mists of Ravenloft.