In document ISO/CD 10303-226, a fault is defined as an abnormal condition or defect at the component, equipment, or sub-system level which may lead to a failure

Failure

Failure refers to the state or condition of not meeting a desirable or intended objective, and may be viewed as the opposite of success. Product failure ranges from failure to sell the product to fracture of the product, in the worst cases leading to personal injury, the province of forensic...

.

According to the Federal Standard 1037C

Federal Standard 1037C

Federal Standard 1037C, titled Telecommunications: Glossary of Telecommunication Terms is a United States Federal Standard, issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended....

 of the United States, the term fault has the following meanings:

1. An accidental condition that causes a functional unit to fail to perform its required function.
2. A defect that causes a reproducible or catastrophic malfunction. A malfunction is considered reproducible if it occurs consistently under the same circumstances.
3. In power
   Electric power
   Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt.-Circuits:Electric power, like mechanical power, is represented by the letter P in electrical equations...
   
    systems, an unintentional short-circuit, or partial short-circuit, between energized conductors or between an energized conductor and ground
   Ground (electricity)
   In electrical engineering, ground or earth may be the reference point in an electrical circuit from which other voltages are measured, or a common return path for electric current, or a direct physical connection to the Earth....
   
   . A distinction can be made between symmetric and asymmetric faults.

Failures in hardware can be caused by random fault

Random fault

A random fault is a fault that occurs as a result of wear or other deterioration. Whereas the time of a particular occurrence of such a fault cannot be determined, the rate at which such faults occur within the equipment population on average can be predicted with accuracy....

s or systematic fault

Systematic fault

Systematic faults are often a result of an error in the specification of the equipment and therefore affect all examples of that type. Such faults can remain undetected for years, until conditions conduce to create the failure. Given the same circumstances, each and every example of the equipment...

s, but failures in software are always systematic.

See also

• Computer bug
• Defect (disambiguation)
• Anomaly in software
  Anomaly in software
  In software testing, a software anomaly is anything that differs from expectation. This expectation can result from many things like from a document or from a person's view or experiences In software testing, a software anomaly is anything that differs from expectation. This expectation can...