Science fiction is a genre of fiction. It 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). Exploring the consequences of such differences is the traditional purpose of science fiction, making it a "literature of ideas". Science fiction is largely based on writing rationally about alternative possibilities. The settings for science fiction are often contrary to known reality.
The study of science fiction, or science fiction studies, is the critical assessment, interpretation, and discussion of science fiction literature, film, new media, fandom, and fan fiction. Science fiction scholars take science fiction as an object of study in order to better understand it and its relationship to science, technology, politics, and culture-at-large.
The field has grown considerably since the 1970s with the establishment of more journals, organizations, and conferences with ties to the science fiction scholarship community, and science fiction degree-granting programs such as those offered by the University of Liverpool and Kansas University.
Set in 2525, twenty-seven years before the events of Halo: Combat Evolved, the novel tells the story of the United Nations Space Command's first encounter with the alien collective known as the Covenant on the colony world of Harvest, and the beginning of the long war that follows. The novel is an ensemble piece, with the action being narrated from both human and Covenant viewpoint The protagonist is a young Marine, Staff Sergeant Avery Johnson, who also appears in the Halo video games. Upon release, the book was generally well-received and became a New York Times bestseller in its first week. Critics pointed to the novel's success as a sign of the increasing importance of story in video games.