What do you mean by Soak Testing?

- Soak testing is a type of testing where the system is tested over a significant period of time by applying significant load to system to check how the system behaves.

- Soak testing is also called as endurance testing.

- Soak testing is a type of performance testing.

- Soak testing is a non functionality testing.

- Soak testing is carried out to check the memory leaks in the system.

Ex: A system may perform well on calculating the tax of n person in an hour. If calculating the tax of n number of person in 24 hours along with the checking of balancing sheet of bank would result in checking of the endurance of the system or performing soak testing.

Difference between Smoke and Sanity testing

Smoke	Sanity
Smoke test is performed to check if the major functionalities as proposed  in the requirement document is working as expected or not before starting system or regression testing.	Sanity test is performed after system or regression testing is carried out to ensure that major functionalities are working as expected and not broken.
Smoke test is build verification testing	Sanity test is build acceptance testing
Smoke test is carried out to check all the major functionalities of a product. If smoke test fails then the build is declared as unstable and testing is stopped.	Sanity test is carried out to check on  a limited functionalities of a product.

Difference between Verification and Validation

Verification	Validation
Verification is process of ensuring that the product is being build according to the requirement and design specification	"Validation is a process of ensuring that the product is built according to the user need and business requirement"
Verification is "Are we building the product right?"	Validation is "Are we building the right product"
Verification is done before the development phase	Validation is performed after the development phase

Difference between Retesting and Regression testing?

Retesting	Regression
Retest is carried out when a particular defect is fixed and tester has to run through the test cases related only to the defect fixed	Regression testing is carried out to check if the defect which is fixed in the module has affected any other module or not. Here tester has to run through the whole module i.e. the test cases which are already passed too and not a particular test case.
Retest is carried out to check if the prior defect which is logged has been rectified.	Regression testing in laymen term is to check if there are any side effect to the defect fixed.
Retest is a planned testing	Regression testing is generic testing