Reliability prediction stands at the center of many reliability programs across government and industry. The basic principle is to define a rate of failure for all key components in a system and then add them together to obtain an overall system failure rate. This process explicitly considers all components to be in series, which means that if one component fails, the entire system fails. The result gives a conservative estimate of the overall system failure rate.

Over the past few decades, several standards have been developed to assist in conducting this type of analysis. The standards define calculation models for different component types based on test data. With few exceptions, these models assume a failure rate that is constant with time to address the useful life of a component where failures are regarded as random. The bathtub curve is a simple graph that is often referenced when discussing reliability predictions.