Confirmation by examining and providing objective evidence that specified requirements have been fulfilled. In a software development environment, specifically, software verification is confirmation that the output of a particular phase of software development meets all of the input requirements for that phase of development. Whereas validation is the demonstration that, say, the software implements each of the software requirements correctly and completely (that is, that the right product was built), verification is the act of ensuring that the products of a given development phase fully implement the inputs to that phase (that is, the software product was built right).
CriTech Research, Inc. Verification and Validation. [Online, January 2002.] CriTech Research Website. http://www.critech.com/vv.htm.