From Interactivity By Design: Creating & Communicating with New Media by Ray Kristof and Amy Satran (1995, Adobe Press; ISBN 1568302215; Amazon | B&N.com)
||High-resolution commercial typesetting systems produce crisp, easy-to-read type at all sizes. Eight-point and smaller text is common, with 8,10, and 11-point the most common sizes for lengthy documents and books.
||Twelve-point type is the smallest size that’s comfortably readable in many fonts, with others starting even higher.
||Fonts with curved serifs, such as Times, are often said to be the most readable, but any good text font is relatively easy to read.
||All fonts work at large sizes, but at smaller sizes founts should have serifs and strokes of even thickness for best legibility. (There are also ergonomic issues, including eye fatigue, associated with reading on computer screens.)
||Extra-tight spacing is often desirable in display type, and it can be controlled to within hundredths of an inch.
||Tight spacing works on very large type, but anti-aliasing causes edges to bleed together. Spacing is more difficult to control.
|Leading (space between lines of type)
||Leading should be two or more points higher than font size for comfortable reading on the screen. Tight leading in some fonts can cause the bottoms of letters to be cut off.
||Since long unbroken lines are more difficult to read, short columns are recommended, in widths that vary according to type size.
||Same basic rules apply, but since the minimum type size on the screen is larger, column width is less of a factor.
|Color and contrast
||No color restrictions, but higher contrast means better readability.
||The softening effect of anti-aliasing reduces the contrast of letter edges, making extremes of contrast necessary so readers can make out text against background art.
|Amount of text on page or screen
||Not an issue.
||Because the screen has much lower resolution than a page, a screen that’s filled with text can be much harder to read.