Verification and Validation are two terms sometimes used interchangeably and sometimes used with swapped meaning.
The meaning, I think, most widely accepted (e.g. ISO, PMI/ PMBoK, APM & APMBoK, IEEE, BS, DIN…) is:
- VERIFICATION is in-process – ongoing during development of the product. It means ‘is built to standards’ or ‘matches the specification’.
- VALIDATION is of the end result – finalised, if not entirely conducted, at handover. It asks, “Is the Customer Satisfied?”
ISO etc., say Verification is all the continuous in-production processes that often involves testing and measurement. It doesn’t tell us if we’ve solved the customer’s problem but it does tell us we’ve followed good processes to arrive at a result that is what was asked for.
On the other hand, Validation is a final acceptance action; it concludes at the point of transfer of ownership. Mostly it asks, “Is the result Fit For Purpose?”
Accepted deliverables may contain non-conformance from the specification and standards that were raised during verification. The customer may be happy to live with non-conformance.
Verification – Built it right. The inputs are the product, the specification and the contents of the quality system. The outputs are the list of non-conformance (if any).
Validation – Built right thing. The inputs are the product, the list of non-conformances and the customer’s opinions. The result is acceptance (or not).
Of course, anyone is free to use alternate meanings if they wish.