Planetary romance is a subgenre of science fiction in which the bulk of the action consists of adventures on one or more exotic alien planets, characterized by distinctive physical and cultural backgrounds. Some planetary romances take place against the background of a future culture where travel between worlds by spaceship is commonplace; others, particularly the earliest examples of the genre, do not, and invoke flying carpets, astral projection, or other methods of getting between planets. In either case, it is the planetside adventures which are the focus of the story, not the mode of travel.