What is the purpose of the alternate flows in a use case?

The purpose of alternate flows in a use case is to illustrate scenarios that diverge from the main or primary flow of events towards achieving a goal. These alternate flows are essential for capturing various paths that might be taken during the interaction with the system, often addressing different conditions or decisions that can lead to different outcomes. They help in detailing how the system will behave under certain circumstances, thereby ensuring that the requirements are comprehensive and consider different use cases.

In this context, alternate flows can account for situations such as optional steps, variations in user choices, or additional functionality that may not fit into the primary use case path. By defining these alternative paths, stakeholders gain a clearer understanding of system functionality and can prepare for various scenarios that users may encounter. This comprehensive approach also aids in identifying potential issues and areas for improvement within the system's design.