Portable Document Format (PDF) is a file format created by Adobe in 1993. As of July 1, 2008, it’s an ISO standard, which means that the format is open and published so that anyone can create it or use it.
There are many misconceptions about the proper use of PDFs, and today I’m going to try to explain how to properly use PDFs on the Internet. Monday I’ll give a couple of faster, easier alternatives to Adobe’s bloated Reader product and discuss some tools to create PDFs without having to use Adobe’s obscenely expensive Acrobat product.
The advantage that PDF has over other file formats is that it’s a good way to represent printed material exactly as the designer intended it. This advantage makes it good to use for contracts and brochures where the user doesn’t need to change the content and is willing to jump through some extra hoops to view the content in a layout that approximates the printed page. It’s a great format for designers to send to printers because it ensures that the content is displayed exactly as the designer intended.
The disadvantage that PDF has is on the Internet. The Internet isn’t a format that is supposed to resemble the printed page. Because the PDF format – for good reason – isn’t supported by any browser, the user must use a browser plug-in to view the content, souring the browsing experience. For this reason, the use of PDFs on websites should be limited to an optional content delivery mechanism.
An example of a very bad use of PDF is for a website selling real estate. The designer used PDF to send the property information document to the printer. The PDF is uploaded to the website and a link is placed on a sparse page that says “download property information document” for information about this property. This breaks the first rule of accessible website design, which is don’t force the user to use a plug-in or add-on to view content. Most browsers with the plug-in installed open the page in a new tab, breaking another first rule of web design which is don’t open new tabs or windows. Search engines index PDFs, but if you click on a search result that is a PDF you’ll be taken straight to the PDF which lacks a navigational system for the user to get to your main website.
An example of a very good use of PDF is for the same website to have every piece of information within the property document delivered as valid XHTML / CSS on the website page with an optional download for users who want to physically print the information about the property. In this case, the user can browse the property information at browser speeds rather than having to wait for and be confused by the loading of a plugin. Even the example property contracts should be first delivered on the website and also made available as PDF for users who want that method as an option.
The very best use of PDF is to not use it at all, delivering the content by XHTML and the layout by two style sheets, one CSS for the screen and one print style sheet, so that the website looks one way on the screen but when the website is printed it looks like the property information document. This is a more advanced website design technique that I’ll try to cover later.
To summarize, PDF has its uses. Just remember that as a content delivery system on the Internet it falls short.