To be immersed in something is to be inside it and surrounded by it, for example, if you are underwater you are immersed in water. If virtual reality succeeds in creating an artificial environment, you can be inside and surrounded by that environment, in a state of immersion.

virtual reality or total immersion goggles

Virtual reality is a computer simulation that imitates reality. Virtual reality can be used for entertainment or for science. (calculation, etc.) Nowadays, virtual reality is used to heal phobia. It is used to train pilots.

Total Immersion - augmented reality - was created in 1999.

Total Immersion - augmented reality -'s population is 90.