  Metaverse, with the combination of the prefix "meta" (meaning transcending)
and the word "universe", has been deemed as the next-generation (NextG)
Internet. It aims to create a shared virtual space that connects all virtual
worlds via the Internet, where users, represented as digital avatars, can
communicate and collaborate as if they are in the physical world. Nevertheless,
there is still no unified definition of the Metaverse. This article first
presents our vision of what the key requirements of Metaverse should be and
reviews what has been heavily advocated by the industry and the positions of
various high-tech companies. It then briefly introduces existing social virtual
reality (VR) platforms that can be viewed as early prototypes of Metaverse and
conducts a reality check by diving into the network operation and performance
of two representative platforms, Workrooms from Meta and AltspaceVR from
Microsoft. Finally, it concludes by discussing several opportunities and future
directions for further innovation.
