Functional Illiteracy

A condition in which a person has basic reading and writing skills but cannot effectively understand or use written text for everyday tasks such as reading instructions, filling out forms, or comprehending web content beyond simple sentences. UNESCO defines functional illiteracy as having fewer than 4 years of formal education. The condition affects hundreds of millions of people globally — 21.7% of the Brazilian population, for example. Functionally illiterate web users struggle with long sentences, complex vocabulary, passive voice, and dense information layouts. For web accessibility, functional illiteracy is addressed by WCAG Guideline 3.1 (Readable) and particularly Success Criterion 3.1.5 (Reading Level, Level AAA), which recommends providing content at a lower secondary education reading level or offering supplementary simplified versions.