It's one thing to see that a problem exists, but it's quite another to devise a solution. One key part of problem solving is the language we use. Over the years, I've developed many useful terms and mental models. They have proven vital to framing the problem presented by hard-to-use software-based products. In this chapter I will introduce those terms and ideas, showing how they can help bring the benefits of interaction design to our troubled process.

As our economy shifts more and more onto an information basis, we are inadvertently creating a divided society. The upper class is composed of those who have mastered the nuances of differentiating between "RAM" and "hard disk." The lower class consists of those who treat the difference as inconsequential. The irony is that the difference really is inconsequential to anyone except a few hardcore engineers. Yet virtually all contemporary Software forces its users to confront a file System, where your success is fully dependent on knowing the difference between RAM and disk.