Causes of System Failure, Aspects of System Dependability, Importance of Dependability, Critical Systems, Importance of Dependability in Critical Systems, Classification of Critical System, Reliability, Availability and Maintainability, Reliability vs Availability, Relationship between Reliability and Faults, Reliability and Environment, SAFETY, Classification of Safety-Critical Software, System reliability vs System safety, Safety Considerations in Designing the Safety Critical System, System Security, Consequences of External Attack, Considerations for Improving System Security, Safety and Security Related Terminologies.