Dystopian books are often characterized by dehumanization, tyrannical governments, environmental disaster, or other characteristics associated with a cataclysmic decline in society. Dystopian societies appear in many sub-genres of fiction and are often used to draw attention to real-world issues regarding society, environment, politics, economics, religion, psychology, ethics, science, or technology. However, some authors also use the term to refer to actually-existing societies, many of which are or have been totalitarian states, or societies in an advanced state of collapse and disintegration.