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Despite many research advances in interactive computer systems, usability barriers still obstruct access to, and blunt effectiveness of, an every-citizen interface for the national information infrastructure-disenfranchising and disenchanting users across society. As a result, the United States fails to accrue the potentially enormous returns of our collective investment in computing technology. These barriers impede human productivity and have a profound impact on computer users in business, government, industry, education, and indeed the whole nation.

In the not-too-distant past, computer usage was esoteric, conducted mostly by a core of technically oriented users who were not only willing to accept the challenge of overcoming poor usability but also sometimes welcomed it as a barrier to protect their craft from uninitiated "outsiders." Poor usability was good for the field's mystique, not to mention users' job security. Now, unprecedented numbers of Americans use computers, and user interface is often the first thing people ask about when discussing software. To most users the interface is the system. For the "every citizen" of today, communication with the system has become at least as important as computation by the system.

The goals of most organizations include increased employee and organization productivity, decreased employee training costs, decreased employee work errors, and increased employee satisfaction. These are also exactly the benefits of achieving high usability in user interfaces. Too often, especially in government and large businesses, training is used as a costly substitute for usability, and almost as often it fails to meet its goals. Attention to usability by developers no longer requires justification in most quarters: "usability has become a competitive necessity for the commercial success of software" (Butler, 1996).

Achieving good usability requires attention to both product and process. The product, in this case, is the content of the user interaction design and its embodiment in software. An effective process for developing interaction design is also important, and a poor understanding of the process is often responsible for a product's lack of usability. While state-of-the-art user interaction development processes are based on formative usability evaluation in an iterative cycle, much of the state of the practice is fundamentally flawed in that remarkably little formal usability evaluation is performed on most interactive systems. This is generally changing now in many industrial settings. However, ensuring usability remains difficult when evaluation, because of real or perceived costs, is not standard practice in interactive software development projects.