From the First Edition's Preface:

THIS BOOK IS FOR ALL THOSE who wish to publish durable content on the Web. Durable content is not guided by trends; good design will withstand the test of time, whereas trends quickly become frivolous. Success in Web design goes beyond technology and fashion. To create Web sites that endure you need only to communicate your ideas clearly and effectively to your readers.

Our purpose for writing this book is to offer basic design principles that you can use to make your content as easy to understand as possible. We explain how to use design as a tool, not as an objective; your Web design should be almost transparent to the reader. We show you how to create a user interface that will allow visitors to your site to navigate your content with ease. We offer suggestions on how to write Web documents; this is a new genre with its own style and guidelines. We delve deep into Web images — color, resolution, compression, and formats — and discuss the benefits of publishing images on the Web. We cover the stylistic and technical issues surrounding the addition of dynamic media to your Web site. All the guidance we offer shares a single purpose: to make your message clear to your readers.

This is not an HTML manual, nor is it a book on graphic design. It is a practical guide to help you design Web sites for the long run.

From the Second Edition's Preface:

The guidance we offer in Web Style Guide has always been grounded on the functional aspects of design. In this second edition we extend our focus on functionality with additional sections on Web site accessibility, Cascading Style Sheets, and flexible page design. We include additional sections on information architecture, site maintenance, and multimedia design. And we have added illustrations and updated our Web site examples to reflect current best practices.