Bug

A bug is a defect that causes a system or product to behave differently from the expected result.

The problem may appear in requirements, design, code, configuration, or data. For example, a bug may cause a system to display an incorrect value or fail to complete a process.

Teams usually record the steps to reproduce the issue. In addition, they document the expected result, the actual result, the affected version, and the operating environment. Therefore, developers and testers can analyse the problem more reliably.

In formal terminology, an error describes a human mistake. A fault describes the incorrect element in a requirement, design, or implementation. Meanwhile, a failure describes the observable incorrect behaviour.

Teams classify defects by severity and priority. Then, they correct the cause and verify the change through testing. Moreover, regression tests check whether the correction affects other functions.

Clear defect reports support efficient analysis, correction, traceability, and quality improvement.