Definition
Screen reader
Software (JAWS, NVDA, VoiceOver) that speaks digital content aloud for blind and low-vision users. For PDFs it reads the tag structure — which is why untagged files are effectively unreadable.
A screen reader is the reason document structure matters: it can only navigate what the file encodes. Headings enable jumping, table tags enable row/column reading, artifacts keep furniture silent. Testing output with one is the gold-standard spot check.
Related tools & guides
Check whether your PDF is accessible
Ceereo audits any born-digital PDF against PDF/UA and WCAG machine checks for free, then writes the missing accessibility layer into the same file. The document looks exactly the same afterwards.