Testing based on requirements involves creating test cases that are developed from the test conditions and objectives which are derived from the requirements. This method guarantees that the tests cover the intended functionalities of the system adequately. To illustrate, requirements-based testing can be used to test particular functions or assess non-functional characteristics such as usability or reliability. By utilizing requirements as the foundation for testing, developers can create test cases that are more efficient and effective in ensuring that the system performs as expected.