Anatomy of Type: The Structural Geometry

Mastery of typography requires an intimate understanding of letterform anatomy:

• Baseline: The invisible horizontal line upon which all letterforms rest.
• X-Height: The height of lowercase letters (such as 'x', 'a', 'e'), excluding ascenders and descenders. Typefaces with tall x-heights (e.g., Inter, Roboto) remain legible at significantly smaller sizes on mobile displays.
• Cap Height: The height of capital letters measured from the baseline.
• Ascender: The portion of a lowercase letter that extends above the x-height (e.g., 'd', 'h', 'k').
• Descender: The portion of a lowercase letter that drops below the baseline (e.g., 'p', 'y', 'g').
• Counter: The enclosed or partially enclosed negative space inside a letterform (e.g., the hole inside 'o', 'e', or 'p').