Legibility

The visual clarity with which individual characters, words, and blocks of text can be distinguished and recognised. Legibility is influenced by font choice (sans-serif fonts are generally more legible on screen), font size (minimum 12px recommended for dyslexic users), letter spacing, line spacing (1.5-2x recommended), line length (60-70 characters optimal), text alignment (left-aligned preferred over justified), colour contrast between text and background, and the avoidance of italics and all-capitals. Legibility is distinct from readability, which concerns the cognitive ease of understanding text content. Both are important for web accessibility: a text can be highly legible (clear, large font) but have poor readability (complex vocabulary), or vice versa.