Virtual World
Virtual Worlds are persistent environments that enable interaction and persistence between multiple people.
This includes non-graphical environments dating back to multiuser dungeons (MUDs) and bulletin board games—and since around the late 1990’s, more graphical massively multiplayer online games (MMOs and MMORPGs).
Virtual Worlds frequently have virtual economies with currencies and virtual items as well as opportunities for creators to contribute and customize.
Further Reading
How Virtual Worlds Work, series by Raph Koster, leading innovators of MMOs.
The Virtual Economy, compare/contrast of closed centralized economies (Fortnite), open centralized (Minecraft) and open decentralized (Decentraland).