The Practitioner's Guide to Military Modeling and Simulation (M&S) is a blend of math and simulation that is updated to reflect the technological progress in the 2020s. A practitioner is a person engaged in the practice of a profession, occupation, etc. So, this book is for professionals that delve in military M&S. Practitioners use simulation for a number of applications, including training, material acquisition, operational testing, and analyzing military problems. Practitioners use simulation when the employment of actual military equipment is impractical, unsafe, extremely expensive, etc. The Practitioner's Guide to Military Modeling and Simulation is comprised of categories or parts of modeling and simulation, including agent-based, discrete event, Monte Carlo, Markov process, physics-based M&S. It includes content on the digital transformation, scenario development, queuing theory, and operational availability (AO). It incorporates examples of M&S software and systems, including ExtendSim, SimPy, AgentPy, SEAS, VR-Forces, MATLAB & Simulink, AnyLogic, STK, America's Army, SIMNET, and others. The Practitioner's Guide Military Modeling and Simulation assumes a basic understanding of the tactics, techniques, and procedures (TTP) prevalent in military science today. However, much of the content describes the capabilities and intended uses of M%S software and systems.