Portable Document Format (PDF) is a file format created by Adobe for the interchange and viewing of files originally created in various different formats. The PDF file format is very popular for providing downloads from web sites but until recently was not readily accessible to access technology.
Which version?
Latest versions of the creation and reader software for PDF files can support accessibility particularly for screen reader users. However, it is important to note that PDF files, and in particular earlier versions, will not be accessible if they are merely presenting an image of a document.
Are the latest PDF files accessible then?
Unfortunately PDF files are only really accessible if they have been created to be that way. Even if a PDF has been created using the very latest software it does not necessarily mean it will be accessible.
Typically, an accessible PDF document will have properly styled heading levels, it will have been saved as a tagged PDF and any images will have had alternative text added.
Further information can be found on the Adobe Accessibility web site.
The bottom line
Unfortunately as yet there is no definitive answer as to whether PDF files are accessible or not. So much depends on how the original document was created and what options, such as tags and alt text, have been implemented in the creation of the PDF file.
Certainly, a properly styled document converted to PDF with accessibility in mind should present no particular problems to the latest screen reader software.
To ensure accessibility it is good practice to also offer any PDF document in an alternative format such as plain text or Word.
Information on other file formats is available on the pages for Word documents, Excel spreadsheets, Powerpoint presentations and ODF documents.