Located on the obscurely named Story palette, Optical Margin Alignment hangs your punctuation outside the edges of the text frame, preventing the appearance of visual holes on the right edge of your type. You get most benefit from Optical Margin Alignment working with justified type, but because it also adjusts the spacing on the left of your text frames, it benefits left-aligned type, too, although less dramatically. With your Type cursor inserted in a story, simply check the Optical Margin Alignment box and you instantly have optically aligned type, the like of which would have taken hours to achieve manually. The type size should, in theory, be set to the same size as the type size you’re using, but you may find it worth experimenting to get the effect you want. Note that while it may get you halfway there, Optical Margin Alignment is not the solution for hanging punctuation, for which you’re better off using the Indent to Here character (Command/Ctrl+\).
The Story palette located under the Type menu. Note how turning on Optical Margin Alignment makes the hyphens and punctuation stick out beyond the edge of the text frame.