Let me describe a familiar user assistance experience. A user installs a new application, and when the user wants Help, the application directs her to the user documentation on a Web site or CD-ROM. What the user finds there is a PDF file containing the manual—or a collection of PDF files, representing a library of manuals, including a user guide, configuration guide, troubleshooting guide, and various references. And the layout of each of these PDF manuals is exactly the same as if it were a printed book. This raises an interesting question: If we’re giving manuals to users to read online, why do we design and write them for paper?