If you ask why something works and you push back far enough, eventually everything seems to be based on contrast: the ability to distinguish one thing from another. Composition, sequencing, even legibility all rely on devices that affect the contrast between things.
— Chris Pulman, The Education of a Graphic Designer

We seek clarity, order, and trustworthiness in information sources, whether traditional paper documents or Web pages. Effective page design can provide this confidence. The spatial organization of graphics and text on the Web page can engage readers with graphic impact, direct their attention, prioritize the information they see, and make their interactions with your Web site more enjoyable and efficient.

Visual logic

Graphic design creates visual logic and seeks an optimal balance between visual sensation and graphic information. Without the visual impact of shape, color, and contrast, pages are graphically uninteresting and will not motivate the viewer. Dense text documents without contrast and visual relief are also harder to read, particularly on the relatively low-resolution screens of personal computers. But without the depth and complexity of text, highly graphical pages risk disappointing the user by offering a poor balance of visual sensation, text information, and interactive hypermedia links. In seeking this ideal balance, the primary design constraints are the restrictions of HTML and the bandwidth limitations on user access ranging from slow modems to high-speed connections such as Ethernet or DSL.

Visual and functional continuity in your Web site organization, graphic design, and typography are essential to convince your audience that your Web site offers them timely, accurate, and useful information. A careful, systematic approach to page design can simplify navigation, reduce user errors, and make it easier for readers to take advantage of the information and features of the site.