This document provides an overview of virtual reality (VR) technologies. It defines VR as a 3D computer-generated environment that a user can interact with via specialized equipment. It describes common VR hardware like headsets, gloves, and suits. It also discusses the different processes involved in VR like visual rendering and audio rendering. The document then outlines several applications of VR in fields like military training, medicine, engineering, entertainment and more. It notes both the positive impacts of VR in providing risk-free experiences, as well as challenges like eye strain, addiction, and difficulty distinguishing virtual from real. Finally, it speculates about future possibilities for more immersive VR through memory implants and shared virtual experiences.