Every user interface designer is familiar with the procedure to some extent: To find out what a user interface needs to look and behave like it’s certainly a good idea to create a prototype and evaluate it with potential users. Users will tell you what’s still nagging them and therefore should be improved before coding starts. So, in the beginning of any UI design process everything is about change – you create a prototype and already expect it to require modifications in order to work alright. As you – and most likely your client, too – want changes to be as cost-efficient as possible, you are better off taking a change-friendly prototyping method or tool. This is especially true in early stages of the project your ideas of potential solutions are rather vague. In this early phase, most often you don’t even know the exact problem for which you are in hunt of a solution. You are still analyzing more than you are designing.