Imaginary histories

Counterfactual history (also virtual history) is a form of historiography that attempts to answer the What if? questions that arise from counterfactual conditions. Counterfactual history seeks by "conjecturing on what did not happen, or what might have happened, in order to understand what did happen." It has produced a literary genre which is variously called alternate history, speculative history, allohistory, and hypothetical history.