The Portable Document Format (PDF) is a file format developed by Adobe Systems. PDF makes it possible to distribute documents with original formatting intact. PDF files are created by scanning an original print document or by using a variety of popular software applications.
The popularity of PDF has created concerns about accessibility, particularly for users of screen readers and for those who have low vision. While Adobe has taken steps to permit access to those who use screen readers, it is essential that documents be correctly marked up (commonly referred to as “tagged”) so that screen readers have the information they need to identify items such as headings and alt text for images. Tables must also be marked up so that screen reader users can navigate them and clearly understand the association of data with appropriate column and row names.
Few authors are currently creating tagged PDF files, either because this requires additional effort or because of lack of awareness. Authors are also limited by the capabilities of their word processing or desktop publishing tools, many of which have PDF export capabilities that do not currently support tagged PDF. Microsoft Office, particularly with its most recent versions, does provide good PDF exporting, assuming that appropriate styles are used when first creating a document in Word.
Adobe provides accessibility documentation at adobe.com/accessibility. Among other resources available from this site, Adobe has developed a variety of Acrobat accessibility training resources that describe in detail the process of creating accessible PDF documents using Word, InDesign, and Acrobat.
Support In Operating Systems
PDF accessibility also requires support from operating system and assistive technology developers. In Microsoft Windows, both JAWS and NVDA support tagged PDF. However, there is currently no support for tagged PDF in other operating systems.
Is PDF the Correct Choice of Format
Despite advances in accessibility, many users and advocacy groups continue to recommend that PDF documents be accompanied, or replaced, by alternative format documents that are more universally accessible, such as HTML. PDF unfortunately is still not indexed as well as HTML and so if content is to be used for SEO then it is often converted to HTML.