"An important area of application for VR systems has always been training for real-life activities. The appeal of simulations is that they can provide training equal or nearly equal to practice with real systems, but at reduced cost and with greater safety. This is particularly the case for military training, and the first significant application of commercial simulators was pilot training during World War II. Flight simulators rely on visual and motion feedback to augment the sensation of flying while seated in a closed mechanical system on the ground."