# What is a tagged PDF?

Source: https://epublab.com/glossary/tagged-pdf/ (updated 2026-11-03)

A tagged PDF contains a structure tree that marks headings, paragraphs, lists, tables and the reading order, on top of the drawn text. Tags are what screen readers use, and PDF/UA requires them.

## Why it matters when you convert a PDF to EPUB

When tags are present and correct, they tell a converter the structure directly. Many PDFs have no tags, or tags generated badly, so a converter cannot rely on them and has to infer paragraphs, headings and reading order from the positions and sizes of the text.