Retesting: Testing the actual defects module or test cases which failed in last execution cycle. Retesting is kind of confirmation testing which check the actual defect got repaired and test case is getting passed.

Regression Testing: Regression Testing is carried out to confirm whether a recent program or code change has not adversely affected existing features

Severity: It is basically Impact or extent to which a defect can affect the application. Types of Severity: Critical, Major, Moderate, Minor,Cosmetic. Priority: It is the urgency in order to FIX the defect. Type of Priority: Low, Medium, High