This book presents essential methods and tools for research into the reliability of energy systems. It describes in detail the content setting, formalisation, and use of algorithms for assessing the reliability of modern, large, and complex electric power systems.  The book uses a wealth of tables and illustrations to represent results and source information in a clear manner. It discusses the main operating conditions which affect the reliability of electric power systems, and describes corresponding computing tools which can help solve issues as they arise. Further, all methodologies presented here are demonstrated in numerical examples. Though primarily intended for researchers and practitioners in the field of electric power systems, the book will also benefit general readers interested in this area.