Joe Clark's article at A List Apart defends the accessibility of Portable Document Format (PDF) documents. You may know them as Acrobat documents because they are most likey read by your Acrobat Reader application from Adobe. (Mr. Clark takes great pains to disassociate PDF from Acrobat.)
One big argument against PDF has been that screen readers, those specialized readers for sight impaired individuals, could not understand PDF documents well. Mr. Clark argues that screen reader improvements combined with markup changes within the PDF document itself can provide an acceptable level of accessibility.
Most Are Unnecessary
Despite Mr. Clark's yeoman work in this area, the fact remains that most PDFs on the internet are unnecessary and better handled by good old (X)HTML. Mr. Clark stands in agreement with this statement as well.
When a client wants to add PDF content, my response (in kinder terms) is: "PDFs show pictures and text -- the CMS you have shows pictures and text. Explain again why you want PDF support."
If I'm out of line, then let me know -- but when I dig down just a little to determine motives, the real reason folks want PDF content is so they can go nuts with fonts and rainbow colors and clip art and "express themselves" in a manner that is completely inconsistent with the rest of the website. In effect, they are circumventing the company's brand to promote their own. All the usability studies that promote and defend the usefulness of web site consistency are thrown out the window.
Most often, someone wants to create an eye-catching (read: obnoxious) flyer to post on the walls of the business then post it to the website. Why? So visitors can tack it onto their refrigerators like some kindergartner's artwork? I really think this is a misuse of the technology and that internet visitors would be better served by standard text and imagery provided by the existing content management system.
The whole website user experience is marred when some PDF reader launches, the user stares at the Acrobat splash screen du jour for six or seven seconds and then some other window appears where the information the user requested must be read. Once finished, the website visitor must then find the browser window that launched the PDF document in order to continue his or her visit. Imagine the back-and-forth necessary if PDFs were launched four or five times per visit! Personally, I wouldn't want to come back.
This sounds, I'm sure, like PDF bashing but that is not my intent at all. PDFs are perhaps the best mechanism to distribute entire brochures or corporate annual reports, or any type of multi-page report, especially if specific layouts or charts or scientific notation is involved. My complaint is against the one-page PDF flyers with fewer than two hundred words within. By and large, Internet visitors would be better served by a cut-and-paste into plain text.
That's how I see it.