Verification and Validation

Verification ensures that the product is built according to the requirements and design specifications.
answers to the question, "Are we building the system right?"

Validation: is done at the end of the development process and takes place after verification one completed. answers to the question, "Are we building the right system?"

Verification and Validation are an independent procedure that is used together for checking that a product, service, or system meets requirements and that it fulfils its intended purpose. 

Suppose, we want to buy a 32 GB memory. We're going to the store, have to see the appropriate product for us, memory written on 32 GB. This is verification. But then we use it and find that we have only 16 GB. The process of finding the error is validation.