Dependability: a generic term encompassing the concepts of reliability, availability, maintainability, security, etc. It is also simply designated by the term "reliability", which underlines its quantitative aspect.

The aim of reliability is the study of systems (sets of elements - hardware, software, human resources - that interact with a view to accomplishing a mission) that are subjected to physical processes such as the processes of failure, repair, and stresses.

The component is a part of a system which is non-resolvable within the framework of the study for which sufficient qualitative information (functioning, modes of failure, etc.) as well as quantitative information (failure rate, repair rate, etc.) has been provided in this study. The notion of component is relative and depends on the study. For example, an aircraft, within the framework of a study dealing with flight safety, represents the system, whereas for the airline company it represents a component.

The study of failures in components has led to very elaborate classifications. The failures that have been taken into account in this book are catastrophic failures, that is to say, they are sudden and complete.

As for reliability, the part that deals with the modeling of the components with a view to obtaining qualitative and quantitative information is called "component reliability" or "reliability statistics". Another part of reliability, called the "reliability of systems", is concerned with the modeling of systems with a view to studying their reliability according to the reliability of their components. The reliability of the systems and...