In Modelling & Simulation, Modelling is the process of representing a model which includes its construction and working. This model is similar to a real system, which helps the analyst predict the effect of changes to the system. Simulation of a system is the operation of a model in terms of time or space, which helps analyze the performance of an existing or a proposed system. In this tutorial, we will discuss the concept and classification of Modelling & Simulation, their architecture, application areas, and other key ideas.