UX Glossary · T
Typography
The arrangement of type: face, size, spacing and hierarchy. On most screens it is the majority of the design.
Typography is the selection and arrangement of type. On a typical interface it accounts for most of what the user actually looks at, which makes it the highest-leverage visual decision and the one most often treated as a preference.
The measurements that matter
Line length. Roughly 45 to 75 characters is the usual guidance for comfortable reading. Much longer and the eye loses the return; much shorter and rhythm breaks.
Line height. Around 1.5 for body text, tightening as size increases. Large headings need proportionally less. WCAG success criterion 1.4.12 requires that text remains usable when users override line height to 1.5.
Size. 16 CSS pixels is the browser default for body text and a sensible floor. Smaller is a decision that should be justified, not a default inherited from a design tool.
Contrast. See contrast ratio. Grey-on-grey body text is the most common accessibility failure in otherwise careful designs.
Hierarchy
A type scale with clear steps does most of the structural work in an interface. Sizes too close together produce a page where nothing reads as more important than anything else, which is a hierarchy failure disguised as a typography one.
In practice
Respect the user’s settings. Sizing in rem means someone who has increased their browser’s
base size gets larger text, which is the point. Fixing sizes in pixels overrides a
deliberate accessibility choice.