According to the BABOK® Guide, a requirement is a usable representation of a need that specifies what a stakeholder requires from a solution. A requirement must be verifiable, which means that it can be tested, validated, or confirmed by some objective means. If a requirement cannot be verified, it cannot be successfully implemented, because there is no way to ensure that the solution meets the requirement and delivers the expected value. References: BABOK® Guide, page 10; Business Analysis Expert Certification, CCBA® | IIBA®, section "What Should I know to be CCBA Certified?"