fonts/knowledge/glossary/terms/legibility_readability/content.md

Although both terms are related, legibility is the measure of how distinguishable individual characters and words are to the eye of the reader; readability is the measure of how easy it is to read the text overall. Both are measures of clarity.

Left: Legibility issues present (top) and corrected (bottom) in the headings. Right: Readability issues present (top) and corrected (bottom) in the body text.

It could be argued that legibility often comes down to the choice of typeface and that readability is down to typography—i.e., the choices made after the typeface has been chosen. But bad typography can affect legibility, too—most obviously if the type is too small or if its contrast is too low.