Virtual reality is a computer-generated world that can be interacted with. It tracks the user in real-time using displays like head-mounted displays. There are different types of virtual reality including immersive VR using displays to replace a user's view and telepresence VR allowing remote control. Virtual reality requires specialized hardware like image generators, manipulation devices, and stereo vision to create the illusions of a 3D environment. Virtual reality has applications in fields like architecture, medicine, engineering, entertainment, training, and manufacturing.