**2.1 Augmented and virtual reality: common goal, different approaches**

The reality-virtuality continuum, proposed by Paul Milgram, is a continuous scale, varying between reality (a physical space with no virtual elements) and virtuality (a virtual space with no physical elements). The area between the two endpoints is mixed reality-a space where real and virtual objects are combined in different ratio. It is clear from the scale (**Figure 1**) that augmented reality is closer to the reality than to virtuality, since it is a physical space with integrated virtual elements.

When discussing augmented reality technology, analogies are invariably made with virtual reality. The two technologies have a common purpose-to immerse users and give them a complete and real sense of the world around them, but they achieve the goal in different ways.

Virtual reality replaces physical world with a digitally created one. Users are completely immersed in the artificial environment and cannot see, feel or interact with the physical world around them. Virtual reality is one of the technologies ensuring that people are completely focused on situations in the digital world. But the technology detaches them from the physical world and is not possible to make a connection between what is happening in the digital world and the surrounding reality.

Unlike virtual reality, augmented reality creates virtual objects that overlay the physical world and provide additional details for real objects. It allows users to be in touch with the real world and interact with real objects and people as well as with computer-generated content. The basic idea behind augmented reality is to immerse users in the physical world and give them more information about what they see, but are not able to perceive through their own senses.
