Semantic Tagging

The process of marking up content within a PDF document with tags that convey the semantic meaning and structural role of each element — such as headings, paragraphs, lists, tables, figures, and links — rather than just visual formatting. Proper semantic tagging ensures that assistive technologies can convey document structure to users: screen readers announce heading levels, navigate between sections, identify list items, and understand table relationships. Key requirements include using appropriate tags (P for paragraphs, not Span), maintaining correct heading hierarchy (H1 followed by H2, not H1 followed by H4), marking decorative elements as artifacts, and ensuring all content is tagged. Semantic tagging in PDFs serves the same purpose as semantic HTML in web content — providing machine-readable structure that enables accessible navigation and comprehension.