While there is some overlap in the uses and structures of virtual worlds, games, and simulations and the three often look similar, their differences are profound. Clark Aldrich presents a taxonomy of virtual environments that recognizes both the distinctions and the similarities among virtual environments for learning. All three, he suggests, are points along a continuum, all instances of highly interactive virtual environments (HIVEs). The HIVE framework recognizes the various relationships among virtual worlds, games, and simulations that can help educators, researchers, and builders of virtual environments think more clearly about the usefulness of virtual environments. (Contains 2 figures and 2 exhibits.)