Why This Book, Why Now? It is now widely recognized that in the development of IT systems, the technology driven focus of the past has been eclipsed by a concern for user satisfaction and user productivity. It is well known that usability engineering helps make systems easier to use and more relevant to business needs. The benefits of producing usable computer systems have been proven in careful dollar or pound calculations and any computer user who has interacted with a system designed for usability will enthuse about the benefits and refuse to go back to the bad old days. More and more organizations are starting to take usability seriously. Along with Microsoft and Apple and other IT organizations, we now find banks, insur ance companies, multi-national pharmaceuticals and many other non-IT corpora tions starting to "do something about usability". It seems as if there is plenty of material explaining how to do it. HCI (Human Computer Interaction - or CHI, Computer Human Interaction in the USA) has been studied in academia for several years and there are a range of books on usability engineering for practi tioners from systems engineering and user interface design to usability evaluation. However, as many practitioners have found, although you do need to understand the theories and be familiar with the techniques, applying them in a commercial context is not a straightforward matter.