Software verification and validation

Verification: Have we built the software right? (i.e., does it implement the requirements).

Validation: Have we built the right software? (i.e., do the deliverables satisfy the customer).

The terms verification and validation are commonly used interchangeably in the industry; it is also common to see these two terms incorrectly defined. According to the IEEE Standard Glossary of Software Engineering Terminology:

Verification is the process of evaluating a system or component to determine whether the products of a given development phase satisfy the conditions imposed at the start of that phase.

Validation is the process of evaluating a system or component during or at the end of the development process to determine whether it satisfies specified requirements.

According to the ISO 9000 standard:

Verification is confirmation by examination and through provision of objective evidence that specified requirements have been fulfilled.

Validation is confirmation by examination and through provision of objective evidence that the requirements for a specific intended use or application have been fulfilled.