Abstract2.1. Defining Failure and Failure Modes2.2. Failure Rate and Mean Time Between Failures2.3. Interrelationships of Terms2.4. The Bathtub Distribution2.5. Down Time and Repair Time2.6. Availability, Unavailability and Probability of Failure on Demand2.7. Hazard and Risk-Related Terms2.8. Choosing the Appropriate Parameter