The concept of virtual reality and the wave of research and development accompaning it are creating new forms of simulation that may lead to fundamental improvements in simulation-based training. However, because virtual reality is a relatively new concept within the training community, there seems to be a few misconceptions concerning what virtual realities are, how they are created, and how they can be used. In an effort to clarify readers' understanding concerning virtual realities, this paper examines three dimensions that will describe virtual reality's role and effectiveness in simulation-based training.