Writing use cases and thinking about how the user is going to interact with your system is a very large part of creating correct and defect free software. Besid

Writing use cases and thinking about how the user is going to interact with your system is a very large part of creating correct and defect free software. Besides the obvious "will the user get it" it has a huge benefit when it comes time to design of your test suite. Consider an imperative programming language where you can have null values. A null value most often means that some piece of data is optional or not required for operation. One example of this could be a form field for users to enter their real names. If you're making a social site ala reddit or something else you might want to make real names optional. Hence when someone fetches the real name field or passes it as an argument to another method it could be null. Designing the use cases will help you because when it comes time to write the implementation and test cases you have a concrete understanding of why the value is null. If your program is sufficiently complex this real name field may end up being passed around to several seemingly unrelated modules. Having the use cases drawn up prior to implementation will help you quickly diagnose those crashes or null pointer exceptions and more generally answering the question "Why is this value null?" Edit: Ineligibility ++