The utopia and its offshoot, the dystopia, are genres of literature that explore social and political structures. Utopian fiction is the creation of an ideal society, or utopia, as the setting for a novel. Dystopian fiction (sometimes combined with, but distinct from apocalyptic literature) is the opposite: creation of an utterly horrible or degraded society that is generally headed to an irreversible oblivion, or dystopia. Many novels combine both, often as a metaphor for the different directions humanity can take in its choices, ending up with one of two possible futures. Both utopias and dystopias are commonly found in science fiction and other speculative fiction genres, and arguably are by definition a type of speculative fiction.