This technique, pioneered by Philip K. Dick in The Man in the High Castle, a book I personally recommend, deals with an event in history that happened in a manner different from its actual course. Dick's novel deals with the theme of Nazis winning World War II and the hilarious consequences thereof. Not to be confused with steam punk, a style pioneered by William Gibson and Bruce Sterling in their joint work The Difference Engine. In steam punk novels, an invention or technological breakthrough occurs dramatically before its time in real history. In The Difference Engine, for instance, Charles Babbage succeeds in developing computers at the dawn of the Industrial Revolution. These computers, for which the novel is named, are run by steam, hence the name 'steam punk'.