Simulation and the virtual environment are well established in aerospace design, manufacturing, maintenance, and repair Application of Virtual Reality (VR) infiltrates into every aspect of spacecraft development and astronaut training Several medical specialties have taken advantage of VR and advanced graphic imaging with their ability to better educate, simulate and demonstrate everything from surgical procedures to Magnetic Resonance Imaging (MRI) examinations. A background in 3-D simulation is presented, with an overview of recent technical developments that have helped make VR what it is today. A foundation on human perception of static and dynamic 3-D environments in real life and simulation will be described to help understand needed fidelity improvements on existing VR systems. Works in progress with dynamic educational applications of VR and Artificial Intelligence (AI) are introduced. A large, multi-institutional study by the Human Systems Center at Brooks AFB may prove the educational benefits expected with the virtual classroom of the future. Basic terminology will be defined and integrated with simple, however, technologically advanced examples. Available VR equipment for home, office, industrial and university applications will be briefly discussed.