This paper presents a description of Modelling and Simulation as used in the Virtual Systems Research Centre at the University of Skövde. It also gives a summarized account of issues discussed in previous work such as phases in a simulation project, Verification, Validation and Accreditation, and the use of simulation as a tool to reduce uncertainty. The role of the human in various phases/activities in simulation projects is highlighted. Examples of both traditional and advanced applications of Virtual Manufacturing are given. Examples of the latter are simulation-based monitoring and diagnostics, and simulation-based optimization. Two models for Information Fusion, the OODA loop and JDL-U model, are discussed, the latter being an extension of the JDL model that describes various levels of information fusion (JDL=“joint directors of laboratories”). Subsequently, the activities and phases in a Modelling and Simulation project are placed in the context of the JDL-U model. This comparison shows that there are very strong similarities between the six (0–5) levels in the JDL-U model and activities/phases in Modelling and Simulation projects. These similarities lead to the conclusion that the JDL-U model with its associated science base can serve as a novel reference model for Modelling and Simulation. In particular, the associated science base on the “user refinement” level could benefit the Virtual Manufacturing community.