Any application of typography can be divided into two arenas: micro and macro. Understanding the difference between the two is especially useful when crafting a reading experience, because it allows the designer to know when to focus on legibility and when to focus on readability.
This article by Nathan Ford focuses mostly on a few simple macrotypographic techniques — with a dash of micro — and on how to combine them all to build a more harmonious, adaptable and, most importantly, readable Web page.