Typography is one of my real passions in life. In my very biased opinion, it is a tragically underappreciated art form, covering all aspects of letter usage including (but not limited to) font design, calligraphy, graffiti, movie titles, interface design, signage, typesetting, and logo design.
Do you know the difference between kerning and tracking? Do you know that the typographic word leading rhymes with “heading,” not with “heeding?” If not, you may want to check out Erik Spiekermann and E. M. Ginger’s excellent book Stop Stealing Sheep & Figure Out How Type Works. It’s a great introduction to typography, and goes over the fundamentals of how typography works. The book is filled with illustrations, photographs, and lots of real-world examples to clarify the points being made. In addition to analyzing the visual characteristics of different fonts, the book also focuses on what typography communicates beyond words, letters, sentences, and paragraphs.
If you’re already familiar with the basics of type and typography but would like to learn more, I’d recommend The Elements of Typographic Style by Robert Bringhurst. Denser and much more academic than Stop Stealing Sheep, Elements will explain to you when to use hyphens, en-dashes, and em-dashes; how different x-heights affect legibility; and enough typographic history to make you a first-class typographic smarty-pants.