Verification and Validation (V&V) are steps to determine if a system or component satisfies its operational and system-level requirements. V&V requirements are established during a program to provide adequate direction for system engineers to gauge the progress of a program.
- Verification is a quality control process determining if a system meets its system-level requirements. Inspection and demonstration is the main testing method used in the Verification process.
- Validation is a quality control process that determines if operational requirements are met for the overall system to meet the Initial Capabilities Document (ICD) and Capability Development Document (CDD). The analysis is a testing method primarily used in Validation.
Definition: Verification and validation (V&V) are independent methods and procedures that are used to check if a component, product, service, or system meets its established requirements and specifications and that it satisfies its intended overall purpose.
Purpose of Verification and Validation (V&V)
The purpose of V&V is to provide direct evidence of progress toward ultimately meeting the customer’s requirements. The V&V results ensure that the product will pass the customer’s criteria. Eventually, these results prove that the product performs as specified and indicate how well it will satisfy its operational needs. 
It confirms that a system element meets design-to or build-to specifications. Throughout the system’s life cycle, design solutions at all levels of the physical architecture are verified through a cost-effective combination of analysis, examination, demonstration, and testing, all of which can be aided by modeling and simulation. 
The Validation Process answers the question of, “Is it the right solution to the problem?” As such, this process works in conjunction with the Stakeholder Requirements, Requirements Analysis, and Architecture and Design processes. It evaluates the requirements, functional and physical architectures, and implementation. In the early stages of the system development life cycle, validation may involve independent evaluation of the system requirements, development of prototypes, and simulations, all to validate the system concept.
There are three (3) processes that encompass validation: 
- The review of documentation by an operational authority other than the user to confirm the operational capability. Validation is the precursor to approval.
- The process by which the contractor tests a publication/technical manual for technical accuracy and adequacy.
- The process of evaluating a system or software component during, or at the end of, the development process to determine whether it satisfies specified requirements.
Difference Between Verification and Validation
The main difference between verification and validation is that Verification is focused on making sure system-level requirements are met, while Validation focuses on making sure the system is performing the way it was designed and intended.
- Verification process includes checking documents, design, code, and program
- Validation process includes testing and validation of the actual product
- Verification uses methods like reviews, walkthroughs, inspections, and desk-checking
- Validation uses methods like models, box testing, and non-functional testing
- Verification checks whether a component (software) confirms a specification
- Validation checks whether a component (software) meets the requirements and expectations
- Verification comes before validation
Verification and Validation (V&V) in the Requirements Development Process
There are six (6) basic requirements development steps, and step 5 is to Verify and Validate requirements.
Below is a list of the basic six (6) steps of requirements development.
Requirements Development Steps
Step 5: Verify and Validate Requirements
In step five, each requirement must be verified and validated to ensure that these are the correct requirements. This ensures that the requirements meet the overall objective of the system and all stakeholder needs.
AcqLinks and References:
-  SMC Systems Engineering Handbook – Chapter 7
- Modeling and Simulation Verification and Validation Challenges
- Picture: Verification Flow Chart from Chapter 7 of DAU SE Fundamentals Guide