Verification is mostly paper work. All the design inputs such as specifications, government and industry regulations, knowledge taken from previous designs, and any other information necessary for proper function are compared with the design outputs such as drawings, assembly instructions, test instructions, and electronic design files. The comparison must verify that each requirement in the inputs is accounted for in the outputs. Validation involves creating the product to prove the design, which is then thoroughly tested to validate that the product, as designed, will meet all the necessary requirements defined in the Design Inputs. This step usually entails more time and testing conducted on production models. To make sure that all requirements are fully met, all measurements and tests are done on the validation unit.