The virtual reality world in the film "Ready Player One" is the OASIS. The name is an acronym for Ontologically Anthropocentric Sensory Immersive Simulation, a vast virtual-reality entertainment universe used by much of humanity in 2045.
In the story, the OASIS was created by James Halliday and Ogden Morrow through their company, Gregarious Games. It began as an online game but grew into a social, educational, commercial, and economic world where users could attend school, work, travel, and adopt customized avatars.
After Halliday dies, he leaves behind a contest hidden inside the OASIS. The first person to locate his Easter egg inherits his fortune and control of the virtual world. Wade Watts, using the avatar Parzival, joins the hunt against rival players and the powerful corporation IOI.
A common mix-up is confusing the OASIS with the real-world setting or with Planet Doom, one of its virtual locations. OASIS is the overall virtual universe; its name is also usually written in all capitals because it is an acronym.