Software Testing

What Is Bug, Error, Defect, Fault, Failure In Software Testing?

Article Software Testing


A bug is a result of a programming error because of which a functionality does not give the expected output.


  • Difference between expected output and actual output.
  • By human-made mistake.
    example: cab (Functionality is working but not completely)
  • A human action that produces an incorrect result.
  • A mistake in coding.


  • A defect is any flaw in a software system when there is a difference between an expected and actual result that is a defect.
  • The defect is classified into three categories
    1. Wrong
    2. Missing
    3. Error
  • An error found by the tester is also known as a defect.Example: phone order (If the actual output is different from customer expectation)


  • A single error can lead to one or more default.
  • A fault may lead to failure.
  • A defect expected by the development team it is called a fault.


  • Deviation of the software from its expected delivery or services.
  • In general, a person makes an error that creates a fault in software and that can cause a failure in operation.
  • If the software does not work as per its capacity is called failure.
  • The actual result doesn’t meet the user requirement.
Aditi Zod

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