Three important elements of science fiction are speculation about humanity's future, the impacts of science and technology on people, and settings in an alternate time and place. For example, Frank Herbert's novel "Dune" is a science fiction novel about a future intergalactic society with sometimes drastically changed humans confronting ecological, social and biological conflicts, while "Ender's Game" by Orson Scott Card tells the story of a boy who plays high-tech games that are in reality, deadly combat against alien enemies.
The speculative question "what if?" is the starting point for all science fiction. Many scholars list Mary Shelley's novel "Frankenstein" as one of the first science fiction books. Shelley's book gave an answer to the question of what would happen if a scientist, Victor Frankenstein, used electricity to reanimate a corpse. Other science fiction stories answer questions about what would happen if first contact with aliens occurred or if humans achieved faster-than-light space travel.
Science fiction frequently includes stories about the impact of scientific or technological change on people. For example, H.G. Wells' "The Time Machine" explored the consequences of building a machine that could carry its occupant far into the future. The "Star Trek" television shows and films portray a future "Federation of Planets" that couldn't "boldly go" anywhere without the warp drive that allows the Enterprise to travel between the stars.
Science fiction stories often take place in the future or in alternate universes. The "Star Wars" films, for example, contain many futuristic elements, even though they feature events that happened "a long time ago in a galaxy far, far away." If they are set closer to the present day, they include scientific speculation that differs from ordinary daily life -- as in "The Running Man" book and film, which tell the story of a cop framed for a crime he didn't commit who must survive a deadly TV game show.
Horror is one of the most closely related genres to science fiction. Most people consider "Frankenstein" to be both a horror and a science fiction story. Zombie stories are one of the most popular current types of horror; some have a supernatural explanation, but others do not. For example, the post-apocalyptic world of the television series "The Walking Dead" is the result of a zombie virus. The "Alien" films include gruesome, horrifying alien monsters alongside less-frightening science fiction elements such as cloning and space travel.