This textbook presents a practical introduction to the fundamental aspects of modelling and simulation. It provides the necessary foundations both for those wishing to learn about this methodology and also for those who have a need to apply it in their work. Illustrative examples are drawn from projects formulated within the domains of both DEDS and CTDS. Features: presents a project-oriented perspective; describes an activity-based conceptual modelling framework (ABCmod) for DEDS; includes a new chapter that presents a novel world view, the Activity-Object world view, which eases the translation of a conceptual model specification in the ABCmod framework into a simulation program; contains numerous illustrative examples, useful algorithms, exercises and projects; includes a primer on probability, a concise guide to the GPSS programming environment and an overview of relevant MATLAB features in the appendices; provides supplementary software and teaching support material at an associated website.