Abstract: This book provides systemic and comprehensive treatment of reliability and availability (i.e., dependability) models of complex computing, communication, and network systems. It will be known as not only a classic textbook for any scholar who studies dependability modeling and analysis but also a technical reference for any engineer who develops dependability assurance techniques. This book is divided into six parts: 'Part I. Introduction', 'Part II. Non-state-space models (combinatorial models)', 'Part III. State-space models with exponential distributions', 'Part IV. State-space models with non-exponential distributions', 'Part V. Multi-level models', and 'Part VI. Case studies'. Some parts are further sub-divided into chapters. Thus, the book is well-organized so that readers can easily and explicitly find pertinent approaches and methods and understand how to solve a concrete problem of dependability modeling, evaluation, and analysis. We believe this book makes significant contributions to dependability engineering, as detailed below: