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Why Use PDF Insead of HTML?

Note: the following is a reprint [slightly edited] of a response posted to a WebAIM discussion board. To see the complete discussion, visit the WebAIM discussion archive: "PDF vs HTML".

Since the requirements for creating an accessible PDF document closely mirror the requirements for accessible HTML "conversion", the effort required is approximately equal. However, one is a proprietary format, the other is an "open" and public format. One requires a "free" downloadable "plugin or stand alone app", the other displays natively in all HTML browsers including text only browsers and older versions of browsers - no need to upgrade to the latest version (not that I advocate *NOT* upgrading whenever appropriate and possible). However, this point alone makes HTML inherently more accessible. If the goal of your web site/organization is to achieve a measurable level of accessibility (ie: WCAG Priority A, AA or AAA status), then I would point him to the following: WCAG Priority 2 - 11.1: Use W3C technologies when they are available and appropriate for a task and use the latest versions when supported. Last time I checked, PDF is not a W3C technology, HTML is.

The bigger question is, why is he arguing this point? Most people in the web accessibility field acknowledge that Adobe have made decent strides in improving their tool, but PDF files were, are, and will continue to be cross platform PRINT files, whereas HTML is, was and will always be cross platform monitor display mark up language. I can use the back of a screw driver or the sole of my shoe to pound a nail into the wall, and it will get the job done. But I would rather use a hammer.

Your colleague has done a decent job rebutting (or rather, arguing against) the points made, however he has not (to my mind) provided evidence on the superiority or benefit of using PDF in lieu of HTML. So to him (via you) I ask: why? Why use PDF instead of HTML?

As we move to a more "web-centric" world, not all participants will be using Internet Explorer with the Adobe Plugin. I know this may come as a shock to some, but trust me, it's true. I am not yet aware of an Adobe Acrobat plugin which works for PDAs, Cell Phones, Web ready refrigerators and car dashboards, etc. These tools (toys?) are with us now, and will only continue to proliferate and grow. For this reason, I personally would seek to ensure that my content is available and accessible to everybody, not just the people sitting at a desk with a tower or laptop. As others have pointed out, go ahead and provide the PDF along side the HTML if a print version is truly required, but if you are going to invest effort converting a document from Word or Excel into a format that can be shared via the web, why not go with the original web format - HTML?


John Foliot
Web Accessibility Specialist / Co-founder of WATS.ca
Web Accessibility Testing and Services

Further Discussion

" Adobe Acrobat Accessibility Techniques." – WebAIM, Techniques and Concepts. Conclusions: "It's wonderful that Adobe has made it possible to make PDF files that are accessible to users of screen readers. Acrobat 6.0 takes a huge leap forward, by embedding a text-to-speech synthesizer in the Reader itself. Still, you can't count on users having the right combination of software and expertise to make use of the Reader's extra functionality. It's always a good idea to provide an HTML version in addition to the PDF, even if the PDF is created with accessibility in mind. Acrobat PDF files can be made directly accessible to users of the JAWS and Window Eyes screen readers, but no other screen reader yet supports the ability to read PDF files directly." www.webaim.org/techniques/acrobat.

" PDF format is still not fully accessible." – 2003 Monash Web Workshop Series, Monash University. Summary: "Although there have been significant improvements to the accessibility of PDF documents, they can only be accessed by blind users in a very limited set of conditions. As a result, whenever PDF documents are used on the web, they should always be supplemented by an accessible alternative (in HTML, RTF, or text format)." www.its.monash.edu.au/web/slideshows/accessibility-pdfformat.

" Strategies for PDF Accessibility." – Duff Johnson, Planet PDF. 20 February 2003. Summary: "Adobe's Current Strategy (as described on access.adobe.com): enhance the PDF format with MSAA-aware capabilities (tags) that document developers may use to improve accessibility. This approach is rooted in the belief that accessibility is operationally defined as the ability to interact with the user's choice of screen reader software. Usability is not part of this definition." www.planetpdf.com/mainpage.asp?webpageid=2578.

See also: " Accessible PDF: A Strategic Review" -- www.planetpdf.com/enterprise/article.asp?ContentID=6118.

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