Use case (also known as user story in extreme programming) is one of the most effective ways to describe how particular system should behave when interacting with user in particular situation.
So use case is a great way to let us developers know how you think your system should work after the project is finished and it is implemented.
Along with designing mockups, writing use cases provides you with better understanding of the desired architecture and makes you think about things you couldn’t think of before. So this allows you to save time and money, shaping out your system’s architecture BEFORE development has started.
Another great thing about use cases is that they can easily be used as test cases when doing QA (quality assurance) of your work - testers just use them as a guide moving step by step and checking system’s functionality against it.
Typical user stories or use cases are step by step written examples of user-system interaction.
Traditionally each step starts with “User” or “System”, this is a rule for writing use cases.
Find below an example of a simple use case from one of our projects, this might help you to create them for your projects. You may find more about use cases in Google and Wikipedia.
1. System displays intro screen, “Start game”, “Options”, “About” buttons in the bottom (see mockup 1)
2. User touches “Options”
3. System displays options screen with buttons “10 Questions”, “1 Minute Test”, “3 Minute Speed Test”, the pre-selected option highlighted (see mockup 2)
4. System displays “Cancel” and “Ok” buttons (see mockup 2)
5. User touches “1 Minute Test”
6. System highlights “1 Minute Test”
7. User touches “Ok”
8. System returns to the Intro screen
Exception 1: No option pre-selected
1. System highlights “10 Questions”