A failure-rate curve that is typical of many manufactured items. The curve is divided into three parts.
The first part is characterized by a decreasing failure rate and it represents the period during which poorly manufactured items are weeded out. (It is common in the electronics industry to burn in components prior to actual use in order to eliminate any early failures.)
The second part, which is often characterized by a constant failure rate, is normally regarded as the period of useful life during which only chance failures occur.
The third part is characterized by an increasing failure rate, and it is the period during which components fail primarily because they are worn out. Note that the same general failure-rate curve is typical of human mortality, where the first part represents infant mortality, and the third part corresponds to old-age mortality.