As progress is made on any application, new and different requirements will likely be added. Sometimes these requirements enhance the existing functionality of the application. At other times, these new requirements may conflict with the existing functionalities. When requirements conflict, it's important that issues are resolved so that the proper functionality can be built.
So, what are the changes in requirements you might expect to see? Changes often consist of alterations to a business rule, new features or enhancements, or modifications needed to resolve a bug or defect discovered in the system.
As time goes on, there will often be a need to modify an existing business rule. This may be in response to user feedback, clarification from the business, or a need discovered through use of the system. When the need for change is discovered, then the existing application will need to change. A comprehensive test suite will ensure that the rest of the system...