Sandbox testing is a method of testing changes in a simulated environment that mimics the real one, without affecting the actual production system. Sandbox testing is useful for change management because it allows the testers to evaluate the change before deployment, and ensure that it works as intended, does not cause any errors or conflicts, and meets the requirements and expectations of the stakeholders. Sandbox testing also helps to protect the investment in the existing system, as it reduces the risk of introducing bugs or breaking functionality that could harm the customer experience or the business operations. Sandbox testing also gives the testers more control over the customer experience, as they can experiment with different scenarios and configurations, and optimize the change for the best possible outcome.