Difference between regression,sanity and smoke test?

Regression Testing:

Regression testing is the process of retesting a software application after making changes or adding new features to ensure that the existing functionality has not been affected. The aim is to identify any defects or errors in the software and fix them. Regression testing can be automated or manual, depending on the complexity of the application and the level of testing required. Regression testing is typically performed after major updates or when new features are added to an application.

Sanity Testing:

Sanity testing is a quick check of the software application to ensure that it is functioning correctly after minor changes. The purpose of sanity testing is to verify that the application is stable and that the changes have not introduced any new defects. It is typically performed before regression testing and other types of comprehensive testing. Sanity testing is usually a subset of regression testing.

Smoke Testing:

Smoke testing is a type of testing that checks whether the basic functionalities of the application are working correctly or not. It is a quick test that is performed to verify that the application is stable enough to proceed with further testing. Smoke testing is typically done after the software build has been deployed to ensure that the basic functionalities are working correctly.

In summary, regression testing is focused on ensuring that changes and new features have not caused any issues, sanity testing is a quick check to ensure that minor changes have not broken the application, and smoke testing is a quick test to ensure that the basic functionalities are working correctly.