This book provides an overview of cyber modeling and simulation (M&S), as currently practiced, looking at scenarios, courses of action (COAs), and current M&S and simulation environments. This book ties up the various threads that currently compose cyber M&S into a coherent view of what is measurable, simulatable, and usable to evaluate systems for assured operation. This book will provide the reader with examples of tools and technologies currently available for performing cyber modeling and simulation. The author examines how decision making may benefit from M&S in cyber defense. This book also looks at example emulators, simulators and their potential combination, along with a look at corresponding verification and validation (V&V) processes that provide the operational community with more confidence that cyber models represent the real world.