Today computing systems are more and more complex and they assume more and more responsibilities in all sectors of human activity. Unfortunately, many faults can harm the development or the use of these products. Destructive mechanisms transform faults into errors and finally failures altering the delivered service. For critical systems, the consequences of these failures can be catastrophic, but for most non-critical systems, failures are nowadays unacceptable. Hence, it is necessary to take dependability attributes into account, along the product lifecycle. This book aims at providing a general overview of the dependability of computing systems: impairments and protective means. Issues, concepts and techniques are considered from a system point of view, and are illustrated by both hardware and software technologies. An important pedagogical effort has been made: the explanations are illustrated by 370 figures, 80 examples, and 97 exercises with complete answers. A glossary of more than 500 entries defines the important terms.