It means something which is not real; as simple as ABC! According to the American Heritage Dictionary, virtual means, existing in essence or effect though not in actual fact or form . Technology, which converges to form VR, is itself very sophisticated and hi-tech. This promising technology provides the best way to visualize information, enabling direct interaction for the user.
We live in a world whose properties we have come to know well through long familiarity. A display connected to a digital computer gives us a chance to gain familiarity with concepts not realizable in the physical world. It is a looking glass into a mathematical world.