Future Tense is a partnership of Slate, New America, and Arizona State University that examines emerging technologies, public policy, and society. Excerpted from Experience on Demand: What Virtual Reality Is, How It Works, and What It Can Do by Jeremy Bailenson. In his 1984 cyberpunk thriller Neuromancer--a canonical literary journey in virtual reality--William Gibson introduced the terms "cyberspace" and the "matrix." The words are familiar now, but the way he discusses them still feels new: He calls them "a consensual hallucination." What Gibson suggests is that it won't be the graphics or photorealistic avatars that will make virtual worlds feel real--it will be the community of people interacting within them, bringing the world alive through their mutual acknowledgment of its reality.