Virtual reality (VR) is a term that applies to computer-simulated environments that can simulate places in the real world, as well as in imaginary worlds. Most current virtual reality environments are primarily visual experiences, displayed either on a computer screen or through special stereoscopic displays, but some simulations include additional sensory information, such as sound through speakers or headphones. Some advanced, haptic systems now include tactile information, generally known as force feedback, in medical and gaming applications. Furthermore, virtual reality covers remote communication environments which provide virtual presence of users with the concepts of telepresence and telexistence. Virtual reality has played key roles in several science fiction films and television programs, most notably, The Matrix franchise. It has also been featured in the 1992 film Lawnmower Man and the short-lived television series VR.5.