We all know this intuitively, but we don’t all practice it. Web design guru Jakob Nielsen says 20 words is all most Web page visitors read before moving on, according to Leslie Walker in The Washington Post. Three-quarters of visitors don’t scroll down to see what’s below the first screen. On average, visitors spend only 27 seconds on each Web page, mostly skimming for links and visual clues about where to go next. Nielsen is co-author of a new book, Prioritizing Web Usability.