According to Artem Katasunov, requirements validation is a process to determine whether the requirements defined do not conflict with the expectations of the various system stakeholders and do not conflict with each other. This is a quality control requirement. Validation is the requirement of the requirements document review process to ensure that the software defines the appropriate software that users expect. Define requirements verification as a process to prove that each requirement is met. Verification can be done by logic, inspection, modeling, simulation, analysis, review, testing, or demonstration.