readability

The term readability refers to several the factors that affect our understanding when we read text -- whether that's on a Web page or in a newspaper or book.

These factors include reader interest, legibility (including illustrations), and complexity of sentence structure

There's not much we can do about reader interest -- other than using our storytelling skills to pull a reader in.

Legibility is a function of several factors:

• Typeface
• Type size
• Type weight and style
• Line length
• Leading (space between lines)

For the Web, we already know that sans-serif faces are more legible, due to the low resolution (72 dpi) of the computer monitor. For the same reason, "normal" or roman style is easier to read than italic or bold face.

Research suggests that line lengths of 7-12 average words seems optimal. Unjustified lines are better on the screen as well as in print, because they help the reader's eye to scan the lines. Moreover, few word processing applications and no Web browser is capable of making the sophisticated adjustments needed to make justified type visually appealing. [Exceptions: FrameMaker, PageMaker and Quark]

That leaves us with sentence structure complexity.