Typography exists to honor content.
Robert Bringhurst, The Elements of Typographic Style
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. As readers scan a page they are subconsciously aware of both functions: first they survey the overall graphic patterns of the page, then they parse the language, or read. Good typography establishes a visual hierarchy for rendering prose on the page by providing visual punctuation and graphic accents that help readers understand relations between prose and pictures, headlines and subordinate blocks of text.