What is "alternate history"

n. 1 contrafactual history, a form of scientific speculation used by historians. 2 A genre of historical romance and usually science fiction, with a story background involving ahistorical events occurring after a point of divergence from real history.

Alternate history or alternative history (British English), sometimes abbreviated as AH, is a genre of fiction consisting of stories in which one or more historical events occur differently from reality. These stories usually contain "what if" scenarios at crucial points in history and present an outcome of events alternative to historical record. The stories are the product of conjecture, but are sometimes based on scientific fact. Alternate history can be seen as a subgenre of literary fiction, science fiction, and/or historical fiction; different alternate history works may use tropes from any or all of these genres. Another term occasionally used for the genre is "allohistory" (literally "other history").

Since the 1950s, this type of fiction has, to a large extent, merged with science fiction tropes involving time travel between alternate histories, psychic awareness of the existence of one universe by the people in another, or time travel that results in history splitting into two or more timelines. Cross-time, time-splitting, and alternate history themes have become so closely interwoven that it is impossible to discuss them fully apart from one another.

In French, Italian, Spanish, Catalan and German, the genre of alternate history is called uchronie / ucronia / ucronía / Uchronie, which has given rise to the term Uchronia in English. This neologism is based on the prefix (which in Ancient Greek means "not/not any/no") and the ancient Greek , meaning "time." A uchronia means literally "(in) no time." This term apparently also inspired the name of the alternate history book list, uchronia.net.