There's more than one metaverse

Will there only be one Metaverse in the future? Since October 2021, many virtual worlds suddenly called themselves "Metaverse", but is that justified? What is the meaning behind the pervasive term Metaverse? How can it be approached from a pragmatic and research-oriented point of view, and maybe separated a bit from pure marketing? This paper tries to contextualise the term and thereby offer an orientation for readers from different industries. Based on a review of past and present activities, we will propose our own definition of the term Metaverse. This is applied to analyse different application scenarios before the paper continues with a general discussion. In a direct comparison, we will tabulate some worlds that already call themselves a Metaverse and check them against criteria from our own definition. In conclusion, we present relevant focal points for a potential future Metaverse resulting from this comparison.