Potential system changes are various and can range from modifications as a result of testing to new feature requirements included in change requests. When a change is made to part of an application, it is usually tested to ensure the fix works. Though this is a good practice, it is not always sufficient as it cannot guarantee the quality of the system. Every change to an existing system has a high probability of adversely affecting other functions in that system, causing a ripple effect of defects. A primary goal of testing must be to ensure existing business objectives continue to be met after system updates.