Verification, Validation and Testing

Validation. Doing the right thing:
Checks that output deliverables satisfy the requirements specified in a previous stage’s input deliverables.
Ensures that the work product is in scope, contributes to the intended benefits, and does not have undesirable side effects.
Is performed by inspecting, simulating, or prototyping.
Verification. Doing it the right way:
Checks that a deliverable is correctly derived and internally consistent.
Checks that output and the process conform to the standards.
Is performed by inspecting and reviewing.
Testing. Right things working right:
Checks that a specification is properly implemented.
Is performed by executing the code.