#39. Applying Optical Margin Alignment
In typography, there is a difference between text that is actually aligned and text that is optically aligned. When text is left aligned or right aligned, the edges still look ragged sometimes due to the shape of the characters. For example, punctuation such as quotation marks, commas, and em dashes often cause this problem as do some letters such as "W" and "A." To fix this, InDesign provides optical margin alignmentalso known as hanging punctuationwhich "hangs" the edges of offending characters slightly outside the margins to produce a smoother looking edge (Figure 39a). This is a special effect that you will generally use sparingly for text such as pull quotes; it is not generally used for body text.
Figure 39a. At left, the text is left aligned, but the left edge looks ragged due to the opening quotation marks and the em dash. At right, the text has optical margin alignment, so the quotation marks and em dash hang slightly outside the margin.
Optical Margin Alignment is an attribute of a storywhich consists of all the text in a series of threaded text framesso you cannot apply it to selected paragraphs. As a result, you may need to place text that requires Optical Margin Alignment in separate text frames. To apply Optical Margin Alignment: