ABSTRACT
Most systems, whether man-made or natural, degrade with time. While time itself is not liable for the degradation, it is the relevant phenomena that take place in time that lead these systems to degrade in functionality. The degradation can be caused by wear and tear from regular use, operating conditions that are harsher than anticipated, and last but not the least, design and manufacturing flaws. When the degradation reaches a certain critical level, failure occurs. A system fails when it can no longer perform its intended function satisfactorily. The end user usually defines the failure event(s); therefore, what counts as failure to one end user may not be so for another. It is possible to define failure in many different ways, ranging from not meeting cosmetic requirements to a major disaster that causes loss of property or life. Needless to say, a formal analysis of these events and their likelihood is needed so that failure can be avoided, or at least its likelihood of happening reduced.
