Verification and Validation (V&V) is a series of technical and managerial activities performed by someone other than the developer of a system to improve the quality and reliability of the system and assure the developed product satisfies the user's operational needs. Verification is the assurance that the products of a particular development phase are consistent with the requirements of that phase and preceding phase(s), while validation is the assurance that the final product meets system requirements. V&V can be performed by an outside agency, which is referred to as Independent V&V, or IV&V, or by a group within the organization but not the developer, referred to as Internal V&V. Use of V&V often accompanies testing, can improve quality assurance, and can reduce risk.