This tutorial will describe the fundamental technologies, terms and concepts associated with Modeling and Simulation (M&S) and describe M&S development and application in the Department of Defense (DoD). The tutorial will cover various aspects of M&S including key M&S terms and concepts that describe M&S technology, development, and application. It will include: (a) M&S terminology and concepts used in the Department of Defense (DoD); (b) M&S technology, architectures and interoperability protocols and their role in enabling key functions in the DoD; (c) The processes for developing valid representations of: DoD warfighting capabilities, threat capabilities, natural environment, complex systems, cyber, autonomy, artificial intelligence/machine learning, and human and organizational behavior. The attendee will become familiar with how M&S is used in the DoD for operational purposes - especially training and other areas of direct warfighter support; and the DoD M&S role in enabling key functions of the Department. This tutorial will identify key policies and procedures for DoD M&S and present:  (a) the  role of Verification, Validation and Accreditation (VV&A) in ensuring that credible models and simulations meet the needs of their users; (b) the role of M&S Standards in the Defense Standardization Program and  its role and impact in DoD M&S use; and (c) the function of the DoD Modeling and Simulation Enterprise Community of Practice (MSE_CoP). The tutorial will describe the characteristics and associated challenges of M&S applications within DoD functional areas including: Training, Analysis, Acquisition, Test and Evaluation, Planning, Medical, Mission Engineering, Autonomy, Artificial intelligence, DoD Research and Development/Employment, and Intelligence. The tutorial will also identify accessible DoD M&S information resources and explain the role of the USD (R&E) Modeling and Simulation Enterprise, as the focal point of DoD M&S information, practice, technology, and functional use.