The process of evaluating software during the development process or at the end of the development process to determine whether it satisfies specified business requirements.
Validation Testing ensures that the product actually meets the client's needs. It can also be defined as to demonstrate that the product fulfills its intended use when deployed on appropriate environment.
It answers to the question, Are we building the right product?
Validation testing can be best demonstrated using V-Model. The Software/product under test is evaluated during this type of testing.
User Acceptance Testing