1. Introduction
What is the Metaverseƒ Stephenson coined this portmanteau in his novel Snow Crash, hypothesizing that in the 21st century humans, thanks to goggles, would be immersed in virtual worlds mixed with real ones. And here we are! At the time, however, the technology to realize the Metaverse was still hypothetical, but today Cross Reality (XR or Extended Reality) is a fact. XR is made up of a multitude of technologies and variants, such as Virtual Reality and Augmented Reality, but they all share a single paradigm: seamless interaction between virtual environments, digital objects and people. That is the Metaverse! But it does not exist yet, and all that is Digital is often only a virtual representation of the real world. How much will it cost us, then, to transport all our real world into the virtual oneƒ