PostScript fonts are designed in an em squarea box that is 1000 units x 1000 units. An em is a relative unit the same size as your type and InDesign kerns (and tracks) in increments of 1/1000 of an em. Place your Type cursor between any pair of characters to see how much kerning is appliedthe Kerning field displays the amount in parentheses in 1000s of an em.
When making kerning adjustments, zoom in to a large enough view size to be able to truly evaluate your resultsand then zoom out again to 100 percent view to make sure your changes look appropriate.
Don't overdo it. Along with the ease of kerning comes a tendency to want to fix things that ain't broke in the first place. Most of the letter shapes we knowand have been reading all our liveswere designed so that well-distributed weight would compensate for their odd shapes. Consequently, they fit well with nearly all of their possible neighbors. It takes time to develop an eye for kerning; until you feel confident, be cautious and make only slight adjustments. And make sure you're consistent: If you decide that certain letter combinations require kerning at display sizes, then make sure you kern all the instances of those letter combinations.
Figure 5.8. The Em Square.
A Kerning Anecdote
When I was a wee lad growing up in South London (and long before I cared about type) I spied the large neon sign of a new video store from a distance of about 100 yards. The name of the store was FLICKERS, set in all caps. The letters were very tightly spaced so thatfrom a distancethe LI combination looked like a U. It certainly grabbed my attention, and possibly it was intentional.
Part I: Character Formats
Going with the Flow
Getting the Lead Out
Kern, Baby, Kern
Sweating the Small Stuff: Special Characters, White Space, and Glyphs
OpenType: The New Frontier in Font Technology
Part II: Paragraph Formats
Aligning Your Type
Paragraph Indents and Spacing
First Impressions: Creating Great Opening Paragraphs
Dont Fear the Hyphen
Mastering Tabs and Tables
Part III: Styles
Stylin with Paragraph and Character Styles
Part IV: Page Layout
Setting Up Your Document
Everything in Its Right Place: Using Grids
Text Wraps: The Good, the Bad, and the Ugly