UML Distilled: A Brief Guide to the Standard Object Modeling Language, Third Edition

Chapter 9. Use Cases

Use cases are a technique for capturing the functional requirements of a system. Use cases work by describing the typical interactions between the users of a system and the system itself, providing a narrative of how a system is used.

Rather than describe use cases head-on, I find it easier to sneak up on them from behind and start by describing scenarios. A scenario is a sequence of steps describing an interaction between a user and a system. So if we have a Web-based on-line store, we might have a Buy a Product scenario that would say this:

The customer browses the catalog and adds desired items to the shopping basket. When the customer wishes to pay, the customer describes the shipping and credit card information and confirms ...