The Evils of PDFs.
More and more websites, especially business ones, seem to adding PDFs to their website – yet users are united in their hatred of them. How on earth did this happen.
PDFs are marketed as an easy way to re-use print designs and content online: all you do is export the data from your desktop publishing program as a PDF, throw it on the web for download, and you're done. It avoids the whole question of web design, or of having to break up the data into sections and create links between it. What's more, it preserves things like pictures and diagrams intact, so, in theory, nothing is lost in the transition.
This appeals a lot to big companies that don't want to pay two people (one for print, one for the web), when they see a way to make one do. The saving on web layout looks real to them, because they're never going to be on the receiving end of the content. In short, the reason people use PDFs is that they don't understand the web.
They Require a Plugin.
Like Flash, PDFs require a plugin, with all the downsides that involves. Users have to go and download the plugin (assuming there is a version for their platform and browser at all), and then come back to your site – that is, if they remember.
However, the PDF plugin is even more painful than most. Why? Simply because it takes a ridiculous amount of time to load. It actually has enough time to pop-up a splash screen and explain which parts of the program are loading – this can take anywhere from 10 to 30 seconds, and there's no way to cancel it once it starts. It's painful enough for most users that opening a PDF unexpectedly will cause them to say "argh no, a PDF!" and leave the computer in disgust, only coming back later to close what loaded.
The Layout is All Wrong.
Even if you know you're loading a PDF and you're happy to sit and wait, what you end up with in the end still annoys you, more often than not.
PDF layouts are nothing but 'virtual pages': they're laid out entirely wrong for the screen. You can't see an entire page on your screen at once without making the text tiny, which forces you to scroll. Anyone who's ever tried to scroll a PDF with columns – scroll down, then back up, then down again... – will know the pain this causes.
Opening a PDF is most often an experience of scrolling past a massive table of contents (that hasn't been made into hyperlinks to the relevant pages), and then trying in vain to find what you were looking for somewhere among the pages. The scrolling in the program is painfully slow, and most of the time you end up giving up pretty quickly.
The Reader Often Crashes.
As a final blow, Adobe's PDF reader program, for all its slowness, isn't even all that stable: it has a tendency to crash people's browsers after a while, especially if they try to use any of the browser's buttons. This upsets your visitors to say the least, and they're not likely to come back to your site again after their browser crashes because of your PDF.
But They're Good for Printing.
However, there is one area in which we have to give PDFs some credit. It's their original intended use: to preserve print layouts over the web so that they can be used for printing. If you want to give your visitors something that is best printed out on paper (a complicated graphical page, for example, or an official form), then the best way to make sure that it survives the journey across the web intact is to let them download it as a PDF.
What does all this mean? Well, really, it means that unless you want to upset your visitors, the only time you should have PDFs on your site is when they're linked to like this: 'Download PDF (for printing)'. Any content you put in a PDF should always also be available as HTML.