To err is human, to forgive—design.
Usability is a measure of effectiveness. It describes how effective tools and information sources are in helping us accomplish tasks. The more usable the tool, the better we are able to achieve our goals. Many tools help us overcome physical limitations by making us stronger, faster, and more sharp-sighted. But tools can be frustrating or even disabling. When we encounter a tool that we cannot work with, either because it is poorly designed or because its design does not take into account our needs, we are limited in what we can accomplish.
In designing web sites our job is to reduce functional limitations through design. When we aim for universal usability, we improve the quality of life for more people more of the time. On the web, we can work toward universal usability by adopting a universal design approach to usability.
Here we cover the concepts, principles, and processes for universal usability. Specific techniques for universal usability are woven into context in the chapters that follow.