PDF can make it harder to communicate with your users.
Lazy web managers' use pdf's as the answer to everything. In my view these managers are vile and nasty and their wicked methods prevent effective communication on the web.
Effective web managers' will use pdf's correctly by following techniques based on effective communication, usability and search engine optimisation. If you have to use a pdf, follow these tips to make it accessible.
Here are my reasons for typical problems with pdf's:
Linear and created for print
User error
Jarring scrolling
Crashes computers
Flow of content
Orphaned document
Content dump
Linear and created for print
PDF documents are typically converted from marketing material that was intended for print. It will be written with the intention that the user will read it in some external environment. Therefore, it often contains contextual and background information on the organisation which wastes the users time on the web (they don't need this as they are already on your website!). It will be designed to get the users attention. It will have very large colourful images. It will be a monster file size. Web is not print. People read differently on the web.
User error
Jarring scrolling
As the pdf documents are typically large, you need to scroll through the pages. This will often create jarring as your computer processes the information especially where the file size is large.
Crashes computers
Users system capabilities have improved greatly in recent years. So whilst not as bad as in the past, you're still more likely to crash users' browsers or computers if you serve them a pdf file rather than an HTML page. Especially as most web managers don't pay attention to file sizes. At Aon, I frequently had requests to upload pdf files that were over 4MB in size! Needless to say, this always resulted in a polite refusal.
Flow of content
On the web you are in a hurry. You are time precious. Therefore having to wait for your Acrobat reader to launch so that you can see the content is very frustrating and annoying. To add to this, pdf files are often large files that tend to take a long time to download and are then written for print.
Orphaned document
As the pdf launches into a new application, it's orphaned from your website. You lose the context of the content, the navigation of your website and all the related content. Users can't even find a simple way to return to your site's original location.
Content dump
Most pdf files are immense content chunks with no internal navigation. They also typically not designed for search, aside from the extremely primitive ability to jump to a text string's next literal match. If the user's question is answered on page 51 (yes, these documents do exist), there's close to zero probability that you will locate it.
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