Science fiction film is a film genre that uses science fiction: speculative, science-based depictions of phenomena that are not necessarily accepted by mainstream science, such as extraterrestrial life forms, alien worlds, extrasensory perception, and time travel, often along with futuristic elements such as spacecraft, robots, cyborgs, interstellar space travel or other technologies. Science fiction films have often been used to focus on political or social issues, and to explore philosophical issues like the human condition. In many cases, tropes derived from written science fiction may be used by filmmakers ignorant of or at best indifferent to the standards of scientific plausibility and plot logic to which written science fiction is traditionally held.

The genre has existed since the early years of silent cinema, when Georges Melies' A Trip to the Moon (1902) amazed audiences with its trick photography effects. The next major example in the genre was the 1927 film Metropolis. From the 1930s to the 1950s, the genre consisted mainly of low-budget B-movies. After Stanley Kubrick's 1968 landmark 2001: A Space Odyssey, the science fiction film genre was taken more seriously. In the late 1970s, big-budget science fiction films filled with special effects became popular with audiences after the success of Star Wars and paved the way for the blockbuster hits of subsequent decades.

Fictional film or narrative film is film that tells a fictional story, event or narrative. Narrative cinema is usually contrasted to films that present information, such as a nature documentary, as well as to some experimental films (works such as Wavelength by Michael Snow, Man with a Movie Camera by Dziga Vertov, or films by Chantal Akerman). In some instances pure documentary films, while nonfiction, may nonetheless recount a story. As genres evolve, from fiction film and documentary a hybrid one emerged, docufiction.

Unlike literary fiction, which is typically based on characters, situations and events that are entirely imaginary/fictional/hypothetical, cinema always has a real referent, called the "pro-filmic," which encompasses everything existing and done in front of the camera.

Since the emergence of classical Hollywood style in the early 20th century, narrative, usually in the form of the feature film, has held dominance in commercial cinema and has become popularly synonymous with "the movies." Classical, invisible filmmaking (what is often called realist fiction) is central to this popular definition. This key element of this invisible filmmaking lies in continuity editing. In this style, narrative and characters are foregrounded, helping the audience to lose themselves in the unfolding fiction.

Science fiction is a genre of fiction dealing with imaginary but more or less plausible (or at least non-supernatural) content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities. Exploring the consequences of scientific innovations is one purpose of science fiction, making it a "literature of ideas".

Science fiction is largely based on writing rationally about alternative possible worlds or futures. It is similar to, but differs from fantasy in that, within the context of the story, its imaginary elements are largely possible within scientifically established or scientifically postulated laws of nature (though some elements in a story might still be pure imaginative speculation).

The settings for science fiction are often contrary to known reality, but most science fiction relies on a considerable degree of suspension of disbelief, which is facilitated in the reader's mind by potential scientific explanations or solutions to various fictional elements. Science fiction elements include: