Today Web-related software development seems to be faced with a crisis not unlike the one that occurred a generation ago when in the 1970s. Computer hardware experienced an order of magnitude increase in computational power. This made possible the implementation of a new class of applications larger both in size and complexity, the methods for software development available at that time were not able to scale up to such large projects. The “software crisis” was a fact with its legendary stories of delays, unreliability, maintenance bottlenecks and costs. Now we seem to be starting to deal painfully with a corresponding “web site crisis”. Over the last few years, the Internet has boomed and the World Wide Web with it. Web browsers are the basic user platform of the Internet. Because of the immense potential audience, and because publishing on the web is in principle very easy, the number of web applications has exploded. Most of the web sites are created opportunistically without prior planning or analysis. Moreover, even large mission-critical intranet projects are being started without any regard for methodology. The resulting problems of maintenance and development backlog, so well-known in “classical” information systems, can easily be predicted and will happen on a much larger scale. Because web sites are almost by definition required to adapt and grow, and have to interact with other sites and systems unknown at the moment of creation, these problems will also be much more complex and severe. In addition to the predictable maintenance and development problems, a new problem unknown in classical information systems has emerged: competition for the user’s attention. Especially for commercial web sites it is important to hold the interest of the user and to keep them coming back to the site. If for some reason visitors are not satisfied with the site or cannot find (fast enough) the information they are looking for, there is a high chance that they will leave the site and not return. Much more than in “classical” software systems, the usability of web applications are primordial for their success.