Difference between Defect, Error, Bug, Failure and Fault!

Testing is the process of identifying defects, where a defect is any variance between actual and expected results. “A mistake in coding is called Error, error found by tester is called Defect, defect accepted by development team then it is called Bug, build does not meet the requirements then it Is Failure.”

DEFECT:

It can be simply defined as a variance between expected and actual. The defect is an error found AFTER the application goes into production. It commonly refers to several troubles with the software products, with their external behavior or with its internal features. In other words, a Defect is a difference between expected and actual results in the context of testing. It is the deviation of the customer requirement.

Defect can be categorized into the following:

Wrong: 

When requirements are implemented not in the right way. This defect is a variance from the given specification. It is Wrong!

Missing:

A requirement of the customer that was not fulfilled. This is a variance from the specifications, an indication that a specification was not implemented, or a requirement of the customer was not noted correctly.

Extra: 

A requirement incorporated into the product that was not given by the end customer. This is always a variance from the specification, but maybe an attribute desired by the user of the product. However, it is considered a defect because it’s a variance from the existing requirements.

ERROR:

An error is a mistake, misconception, or misunderstanding on the part of a software developer. In the category of the developer, we include software engineers, programmers, analysts, and testers. For example, a developer may misunderstand a de-sign notation, or a programmer might type a variable name incorrectly – leads to an Error. It is the one that is generated because of the wrong login, loop or syntax. The error normally arises in software; it leads to a change in the functionality of the program.