Virtual reality
Around the same time, Douglas Engelbart used computer screens both as input and output devices. In 1968, Ivan Sutherland, with the help of many students including Bob Sproull, created what was widely considered to be the first head-mounted display (HMD) system for use in immersive simulation applications. It was primitive both in terms of user interface and realism, and the HMD to be worn by the user was so heavy that it had to be suspended from the ceiling. The graphics comprising the virtual environment were simple wire-frame model rooms. The formidable appearance of the device inspired its name, The Sword of Damocles.
Virtual reality headset
The virtual reality headset allows the military personnel to interact with virtual reality people to make it feel real. They can talk to one another and do varying actions to make the virtual reality world feel like they are actually in that situation. There are also disadvantages and advantages when military personnel use the headset. The disadvantage is the headset is made for an indoor area, with a cool environment, and away from any heat, so when military personnel have just the headset on, no military equipment, it is not like their basic training. The advantages consist of repeating the situations multiple times and the cost of having the headset is less, due to no military equipment being needed.