"Typography is the balance and interplay of letterforms on the page—a verbal and visual equation that helps the reader understand the form and absorb the substance of the page content. Typography plays a dual role as both verbal and visual communication."
-- Robert Bringhurst
If you get it right, typography can be incredibly powerful. Typography exists to honor content and when it’s done well it reveals every element, every relationship between elements, and every logical nuance of the text.