Scrolling and Paging
Fundamental choice: will information be presented in a long page that users must scroll, or a sequence of short pages that the user must view in sequence?
1. Eliminate horizontal scrolling (5:4)
Horizontal scrolling is uncommon (and may be overlooked) and is especially bad when readers must scroll back and forth to read each line of text in a passage. Avoid it.
EN: There may be instances in which horizontal scrolling can be used effectively (scrolling a timeline, for example) - but it stands to reason that the designer would have to acknowledge that this is unusual and guide the user to scroll the page horizontally.
2. Facilitate rapid scrolling while reading (2:4)
I think the author means "scanning" rather than "reading" - important items should be placed in bold, large text to catch user's attention while they are in the process of scrolling down a page.
3. Use scrolling pages for reading comprehension (2:4)
Users have better reading comprehension when they scroll, rather than page through, an article. The act of paging (clicking a link to proceed) creates a conceptual break between topics and suggests that previous information is no longer immediately relevant to what is being discussed in the 'new" page.
4. Use paging for separation (2:4)
Provided that individual pages can be loaded in a reasonable amount of time, users are better able to find information on a specific target by paging through a number of short screens than by scrolling a long screen.
5. Scroll fewer screenfuls (2:4)
Consider whether a document can be broken into sections that are focused on subtopics - such that a user may view eight topics of three "screens" of scrolling rather than one topic of twenty-eight "screens"
EN: User research is divided on the issue of whether readers find it easier or more desirable to use a resource that contains long, scrolling screens or screen-sized bites users must click through in serial. It's a matter of personal preference, and statistics do not lean either way.