The system should be verified and validated at each stage of the software development process using documents produced in earlier stages.
Verification and validation thus starts with requirements reviews and continues through design and code reviews to product testing.
Testing may be carried out during the implementation phase to verify that the software behaves as intended by its designer.” Validation can go beyond just the acceptance criteria (though hopefully the upfront discussions of the user stories, business reasons, and acceptance criteria help mitigate potentially not validating something very late in the game.) Some things you just do not know until it’s built, and so you may not be able to fully validate something until an audit or end-to- end workflow or exploratory testing occurs to really identify how usable something is.[caption id="attachment_12887" align="aligncenter" width="550"] Image Source: It is important to both verify and validate your product.Although static verification techniques are becoming more widely used, program testing is still the predominant verification and validation technique.Testing involves exercising the program using data like the real data processed by the program.Validation involves checking that the program as implemented meets the expectations of the customer.