Soft science fiction, or soft SF, is a category of science fiction that uses less probable or realistic science elements. It either (1) explores the "soft" sciences, and especially the social sciences (anthropology, sociology, psychology, political science, and so on), rather than engineering or the "hard" sciences (for example, physics, astronomy, or chemistry), or (2) is not scientifically accurate, or (3) both of the former. Soft science fiction of either type is often more concerned with character and speculative societies, rather than scientific or engineering speculations. It is the complement of hard science fiction. The term first appeared in the late 1970s.