Reliability engineering is
engineering that emphasizes
dependability in the
lifecycle management of a
product. Dependability, or reliability, describes the ability of a system or component to function under stated conditions for a specified period of
time. Reliability may also describe the ability to function at a specified moment or interval of time (Availability). Reliability engineering represents a sub-discipline within
systems engineering. Reliability is
theoretically defined as the
probability of success (Reliability=1-Probability of Failure), as the frequency of failures; or in terms of
availability, as a probability derived from reliability, testability and maintainability.
Testability,
Maintainability and
maintenance are often defined as a part of "reliability engineering" in Reliability Programs. Reliability plays a key role in the
cost-effectiveness of systems.