Typography Theory — Basic Principles for Designers

Article

Typography is not about choosing pretty fonts. It is about controlling the space between letters, lines, and paragraphs so that reading becomes effortless. Every professional designer—whether setting a 400-page monograph or a single landing page—relies on three mechanical principles: kerning, leading, and tracking.

Kerning adjusts the space between two specific characters. Not all letter pairs sit comfortably together. An A next to a V creates a visual gap that the eye interprets as a hole; a T followed by an o can look like it is colliding. Good kerning removes these optical imbalances. In body text you rarely kern manually—modern OpenType fonts handle this automatically via kerning tables. But in headlines, logotypes, and pull quotes, manual kerning is non-negotiable. A practical rule: zoom to 100 %, shift the pair until the white space feels even, and trust your eye over the ruler.

Leading (pronounced "ledding") is the vertical distance between baselines of successive lines. Set too tight and lines blur into a solid block; set too loose and the reader loses the horizontal thread. For body text at 16 px, a leading of 24 px (150 %) is a reliable starting point. Increase leading as font size grows: a 24 px headline might need 32–36 px of leading. Serif typefaces generally require slightly more leading than geometric sans-serifs because their ascenders and descenders are taller. When in doubt, add space before subtracting it.

Tracking adjusts spacing across an entire range of characters, not a single pair. It is the tool you reach for when a block of all-caps text feels dense or when a large headline needs to feel airy and authoritative. Tighten tracking by 5–10 units for short all-caps labels; loosen by 10–20 units for display sizes above 36 px. Never track body text—it destroys readability and breaks the designer's relationship with the reader.

These three controls work together. Kerning fixes local collisions, leading governs vertical rhythm, and tracking sets the overall density. When you adjust one, re-evaluate the others. A paragraph with perfect kerning will still fail if the leading is 120 %. A headline with generous tracking will look loose if the kerning between critical pairs is ignored.

Readability improves when you match typographic scale to reading distance. A subway poster viewed from three metres needs looser tracking and bolder weights than a magazine spread read at arm's length. Test your work at the intended size and distance. Print a proof. Read it aloud. If you stumble, the type is stumbling too.

Infographics

Quick-reference guides you can pin to your desk or keep open in a second monitor.

Resources

Tools, references, and exercises from the LetterLab team and the broader typography community.