When a defect is detected and fixed then the software should be retested to confirm...

When a defect is detected and fixed, the software should be retested to confirm that the original defect has been successfully removed. This process is called confirmation testing (or re-testing). According to the ISTQB CTFL Syllabus, version 4.0, confirmation testing involves re-running a test to verify that a specific defect has been fixed. The main objective of this type of testing is to ensure that the initial defect no longer exists after the fix has been applied.

The syllabus states that confirmation testing is distinct from regression testing, which checks for unintended side effects of changes in the software. Confirmation testing specifically targets the areas where defects were found and fixed to ensure those defects are resolved​​.