A cyborg is a cybernetic organism (i.e., an organism that is a self-regulating integration of artificial and natural systems). The term was coined in 1960 when Manfred Clynes and Nathan Kline used it in an article about the advantages of self-regulating human-machine systems in outer space. D. S. Halacy's Cyborg: Evolution of the Superman in 1965 featured an introduction by Manfred Clynes, who wrote of a "new frontier" that was "not merely space, but more profoundly the relationship between 'inner space' to 'outer space' -a bridge...between mind and matter." The cyborg is often seen today merely as an organism that has enhanced abilities due to technology, but this perhaps oversimplifies the category of feedback.

Fictional cyborgs are portrayed as a synthesis of organic and synthetic parts, and frequently pose the question of difference between human and machine as one concerned with morality, free will, and empathy. Fictional cyborgs may be represented as visibly mechanical (e.g. the Borg in the Star Trek franchise); or as almost indistinguishable from humans (e.g. the Cylons from the re-imagining of Battlestar Galactica). These fictional portrayals often register our society's discomfort with its seemingly increasing reliance upon technology, particularly when used for war, and when used in ways that seem to threaten free will. They also often have abilities, physical or mental, far in advance of their human counterparts (military forms may have inbuilt weapons, amongst other things). Real cyborgs are more frequently people who use cybernetic technology to repair or overcome the physical and mental constraints of their bodies. While cyborgs are commonly thought of as mammals, they can be any kind of organism.

According to some definitions of the term, the metaphysical and physical attachments humanity has with even the most basic technologies have already made them cyborgs. In a typical example, a human fitted with a heart pacemaker or an insulin pump (if the person has diabetes) might be considered a cyborg, since these mechanical parts enhance the body's "natural" mechanisms through synthetic feedback mechanisms. Some theorists cite such modifications as contact lenses, hearing aids, or intraocular lenses as examples of fitting humans with technology to enhance their biological capabilities; however, these modifications are no more cybernetic than would be a pen, a wooden leg, or the spears used by chimps to hunt vertebrates. Cochlear implants that combine mechanical modification with any kind of feedback response are more accurately cyborg enhancements.

The prefix "cyber" is also used to address human-technology mixtures in the abstract. This includes artifacts that may not popularly be considered technology. Pen and paper, for example, as well as speech, language. Augmented with these technologies, and connected in communication with people in other times and places, a person becomes capable of much more than they were before. This is like computers, which gain power by using Internet protocols to connect with other computers. Cybernetic technologies include highways, pipes, electrical wiring, buildings, electrical plants, libraries, and other infrastructure that we hardly notice, but which are critical parts of the cybernetics that we work within.