The Culture is a fictional interstellar Socialist utopian society created by the Scottish writer Iain M. Banks, which features in a number of his space opera novels and works of short fiction, collectively called the Culture series.
In the series, the Culture is composed of several inter-bred humanoid species, as well as artificially intelligent sentient machines, with intelligences ranging from human-equivalent drones, to hyper-intelligent Minds. The Culture's economy is maintained automatically by its non-sentient machines, with high-level work entrusted to the Minds' subroutines, which allows its humanoid and drone citizens to indulge their passions, romances, hobbies, or other activities, without servitude. Many of the series' protagonists are humanoids who choose to work for the Culture's elite diplomatic or espionage organisations, and interact with other civilisations whose citizens hold wildly different ideologies, morals, and technologies.
The Culture has a grasp of technology which is advanced relative to most of the other civilisations which share the galaxy. Most of the Culture's citizens do not live on planets but in or on artificial habitats, such as huge orbitals, or on ships, the largest of which are home to billions of individuals. Biologically, the Culture's citizens have been genetically enhanced to live for centuries, and have modified mental control over their physiology, including the ability to introduce a variety of psychoactive drugs into their systems, change biological sex, or switch off pain at will. Culture technology is able to transform individuals into vastly different body forms but, for unclear reasons, the Culture standard form remains fairly close to human.
A central theme of the series is the ethical struggles which face the Culture when interacting with other societies - some of which brutalise their own members, pose threats to other civilisations, or threaten the Culture itself, the reactions to which conflicting with the Culture's philosophy of peace and individual freedom. The Culture tends to make major decisions based on the consensus formed by its Minds and, if appropriate, its citizens – or, in one instance, its entire population, with the Culture's decision to go to war with a rival civilisation decided by the direct democratic vote of trillions. Those who objected to the Culture's subsequent militarisation broke off from the meta-civilisation, forming their own separate civilisation; a hallmark of the Culture is its ambiguity. In contrast to the many interstellar societies and empires which share its fictional universe, the Culture is difficult to define, geographically or sociologically, and "fades out at the edges".