Science fiction

Science fiction is the genre of speculative fiction that imagines advanced and futuristic changes in technology, scientific knowledge or biological systems. Its toolkit has widened over time: space exploration, extraterrestrial life, time travel and robotics came first, then parallel universes, dystopian societies and biological manipulation, and lately information technology, transhumanism, posthumanism and environmental challenges. Definitions are famously contested. Asimov's covers fiction about "the reaction of human beings to changes in science and technology"; Heinlein's calls it realistic speculation about possible future events, grounded in the real world and the scientific method; Damon Knight concluded that science fiction is whatever we point to when we say it.

The long shelf runs from Lucian's A True Story in the 2nd century CE and Kepler's Somnium (1634), through Frankenstein (1818), often credited as the first true science fiction novel, and the era of Verne and Wells, to Hugo Gernsback's Amazing Stories launching in 1926. Even the abbreviation is a class marker: sci-fi, coined around 1954, was long attached to low-quality pulp and B movies, and plain SF remains the preferred abbreviation among writers and readers. For web-serial writers the useful split is emphasis: hard science fiction keeps the science load-bearing, soft science fiction centers the human sciences, and space opera trades rigor for sweep. See how to write science fiction.