Navigation isn’t just a feature of a web site, it is the web site, in the same way that the building, the shelves, and the cash registers are Sears. Without it, there’s no there there.
Users of web documents don’t just look at information, they interact with it in novel ways that have no precedents in paper document design; therefore, web designers must be versed in the art and science of interface design. The graphic user interface (gui) of a computer system comprises the interaction metaphors, images, and concepts used to convey function and meaning on the computer screen. It also includes the detailed visual characteristics of every component of the graphic interface and the functional sequence of interactions over time that produce the characteristic look and feel of web pages. Graphic design and visual “signature” graphics are not used simply to enliven web pages—graphics are integral to the user’s experience with your site. In interactive documents, graphic design cannot be separated from issues of interface design.