This document summarizes key terms used in typography and letter anatomy: The baseline is the invisible line letters rest on, the x-height is the height of lowercase x, ascenders rise above the x-height like in "d", and descenders drop below the baseline like in "g". Other terms include bowls, counters, serifs, stems, shoulders, cap-heights, terminals, letterspacing, ligatures, and cases for uppercase letters. The document concludes that as the foot has 26 bones, the alphabet has many parts and terms, and learning is never-ending.