What is virtual reality?

Virtual reality is a simulated 3D environment that enables users to explore and interact with a virtual surrounding in a way that approximates reality, as it is perceived through the users' senses. The environment is created with computer hardware and software , although users might also need to wear devices such as helmets or goggles to interact with the environment. The more deeply users can immerse themselves in a VR environment -- and block out their physical surroundings -- the more they are able to suspend their belief and accept it as real, even if it is fantastical in nature.

What are the main types of virtual reality?

The VR industry still has far to go before realizing its vision of a totally immersive environment that enables users to engage multiple sensations in a way that approximates reality. However, the technology has come a long way in providing realistic sensory engagement and shows promise for business use in a number of industries.

VR systems can vary significantly from one to the next, depending on their purpose and the technology used, although they generally fall into one of the following three categories:

• Non-immersive. This type of VR typically refers to a 3D simulated environment that's accessed through a computer screen. The environment might also generate sound, depending on the program. The user has some control over the virtual environment using a keyboard, mouse or other device, but the environment does not directly interact with the user. A video game is a good example of non-immersive VR, as is a website that enables a user to design a room's decor.
• Semi-immersive. This type of VR offers a partial virtual experience that's accessed through a computer screen or some type of glasses or headset. It focuses primarily on the visual 3D aspect of virtual reality and does not incorporate physical movement in the way that full immersion does. A common example of semi-immersive VR is the flight simulator, which is used by airlines and militaries to train their pilots.
• Fully immersive. This type of VR delivers the greatest level of virtual reality, completely immersing the user in the simulated 3D world. It incorporates sight, sound and, in some cases, touch. There have even been some experiments with the addition of smell. Users wear special equipment such as helmets, goggles or gloves and are able to fully interact with the environment. The environment might also incorporate such equipment as treadmills or stationary bicycles to provide users with the experience of moving through the 3D space. Fully immersive VR technology is a field still in its infancy, but it has made important inroads into the gaming industry and to some extent the healthcare industry, and it's generating a great deal of interest in others.

How augmented reality, virtual reality and mixed reality software compare.

Collaborative VR is sometimes cited as a type of virtual reality. In this model, people from different locations come together in a virtual environment to interact with one another, with each individual represented by a projected 3D character. The users typically communicate through microphones and headsets.

Augmented reality also is sometimes referred to as a type of virtual reality, although many would argue that it is a separate but related field. With augmented reality, virtual simulations are overlaid onto real-world environments in order to enhance or augment those environments. For example, a furniture retailer might provide an app that enables users to point their phones at a room and visualize what a new chair or table might look like in that setting.

Another category that is sometimes considered a type of virtual reality is mixed reality, which blends the physical and virtual worlds into a single space. Like augmented reality, however, it is more often considered a separate but related field. In fact, there's been a growing consensus to group virtual reality, augmented reality and mixed reality under the umbrella term "extended reality," which provides a handy way to reference all three, while still distinguishing among them.

Today's VR technologies and applications have inspired multiple companies and experts to advocate for advanced uses of the metaverse.