Virtual reality (VR) refers to the computer-generated simulation of a world, or a subset of it, in which the user is immersed. It represents the state of the art in multimedia but concentrates on the visual senses. VR allows the user to experience situations that are too dangerous or expensive to enter ‘in the flesh’. Users may explore the real world at a different scale and with hidden features made visible. Alternatively, the virtual worlds that are generated may be entirely synthesized: realistic within themselves, but purely a manifestation of electronic structures. The term ‘virtual reality’ conjures up an image of a user weighed down with a helmet or goggles, grasping, apparently blindly, into empty space. The user, within his virtual environment, moves through a simulated landscape, picking up objects on the way. This is fully immersive VR. However, it is only one part of the spectrum of VR, which also includes desktop VR, command and control situations, and augmented reality, where virtuality and reality meet. Virtual reality has been shown to successfully produce environments that mimic our everyday world. Architects have always used models and sketches to show clients how a building will appear. Now, with the use of VR, they can take clients through a virtual tour of the building, fly over it from above, look at it from the streets outside, enter the doors and walk through the corridors. I have also seen techniques used to plan kitchens and even gardens. However, there are also many things that we cannot see, either because they are invisible to the naked eye (heat, magnetism, gravity) or because they are too small or too large. Scientific and data visualization systems make use of VR technology to expose and explore these features. Augmented Reality is another term, often confused with VR. In augmented reality, electronic images are projected over the real world – virtuality and reality meet. The head-up displays in many aircraft and even some automobiles can be regarded as an example of this, but the data in such displays are not typically connected to the objects seen through them and, hence, the blend between virtuality and reality is quite weak. The great difficulty with such systems is in ensuring that the physical and virtual world are correctly aligned, a problem called registration. If not properly registered, a virtual ball would either bounce short of the real wall or else appear to go through the wall and then bounce back from the other side. Augmented reality techniques hold great promise, and have been investigated especially in situations involving the maintenance or assembly of complex equipment. These forms of development I would love to explore more.