The height of lowercase letters in a typeface, measured using the letter ‘x’, affecting perceived size and readability. Fonts with larger x-heights appear larger and more readable at small sizes. Consider x-height when selecting fonts for body text.

Ascenders are upward strokes on lowercase letters that extend above the x-height and influence legibility and typographic rhythm.

Midline is a typographic reference line that aligns the tops of short lowercase letters and helps define x-height proportion.