Non-Designer’s Type Book, The, Second Edition

What Makes a Typeface Readable?

There are several factors that determine whether text is readable. Most typefaces are either high or low on the readability scale simply due to the way they are designed. But a typesetter or designer can make any readable face unreadable, and conversely she can improve the readability of any face. It is your job to be conscious of both.

What makes a typeface intrinsically readable? Mainly it is a matter of a moderation of features, an invisibility. That is, whenever a feature of a typeface becomes noticeable, that face becomes slightly less readable. If a typeface has a very distinctive lowercase g, so distinctive that it makes you stop and say, “wow, look at that g,” then it is lower on the readability scale. ...