Alternate history (also alternative history, althist, AH) is a genre of speculative fiction of stories in which one or more historical events occur and are resolved differently than in real life. As conjecture based upon historical fact, alternative history stories propose What if? scenarios about crucial events in human history, and present outcomes very different from the historical record. Alternate history also is a subgenre of literary fiction, science fiction, and historical fiction; as literature, alternate history uses the tropes of the genre to answer the What if? speculations of the story. Since the 1950s, as a subgenre of science fiction, alternative history stories feature the tropes of time travel between histories, and the psychic awareness of the existence of an alternative universe, by the inhabitants of a given universe; and time travel that divides history into various timestreams. In the Spanish, French, German, and Portuguese, Italian, Catalan, and Galician languages, the terms Uchronie, ucronia, ucronía, and Uchronie identify the alternate history genre, from which derives the English term Uchronia, composed of the Greek prefix ου- ("not", "not any", and "no") and the Greek word χρόνος (chronos) "time", to describe a story that occurs "[in] no time"; analogous to a story that occurs in utopia, "[in] no place". The term Uchronia also is the name of the list of alternate-history books, uchronia.net. Moreover, Allohistory (other history) is another term for the genre of alternative history.