Although early efforts focused on the potential of immersing oneself in a VE, more recent work has suggested that a combination of reality and VEs might also be useful. This notion is depicted in Figure 25.2, where we see a real-world-to-VE continuum. The "real world" end of the continuum represents what we perceive in the real world, whereas the VE end represents a simulation of an environment. In between, we see mixed environments (MEs (or mixed realities (MRs), which represent a combination of the real world and a virtual representation. The notion of MEs can be further subdivided into augmented reality and augmented virtuality, depending on whether the real world or the virtual representation is emphasized.