Technically, PDF is not considered a true ebook format because it doesn’t offer reflowable text allowing readers to easily change the font and size to suit their reading conditions. This makes sense because, after all, PDF was designed from the start to serve as a page description and layout format optimized for printing.

But, since PDF is such a common format, many of the more feature-rich ereaders offer at least some degree of support. The challenge to both ereaders and users are twofold however.

First, because you cannot easily reflow text in a PDF document, these books can be difficult to read on devices with small screen.

Second, PDF was designed for platforms with quite a bit of horsepower, such as desktop and notebook computers and high-end laser printers. Some ereaders struggle to correctly format and present complex PDF documents.

Having said that, PDF has become an established corporate standard and is ideal for documents that absolutely require delicate attention to typography and rely on the layout of the page to convey important information to the reader.

Understanding PDF Features

PDF files support essentially all the features that we commonly associate with well-designed books because, perhaps not suprisingly, many of the print books we read are, at one point, either stored, proofed, transmitted, or printed from a PDF file.

This includes support for advanced typography, cross-references and hyperlinks, tables, illustrations and photos, as well as multimedia and interactivity (including audio, video, and interactive forms).

Strengths

The principal strength of PDF is that it is a well-developed and mature format that has evolved to support essentially all the features that we associated with modern books (and other documents). Another strength is that we, as a community, have a large body of experience with PDF and the tools used to create files in this format.

Weaknesses

The principal weakness of PDF is that files stored in this format are not easily reflowable. This means that PDF books created to be printed on standard legal (or A4) size paper do not typically display well on smaller screen ereaders such as the Amazon Kindle or the Barnes & Noble NOOK.

The problem becomes even more acute with mobile devices such as smartphones and ultraportable ereaders designed to fit in a large pocket or small purse.

Our Recommendation

Few of the major ebookstores, such as Amazon or Barnes & Noble, currently feature PDF-formatted books for sale. However, many independent publishers—especially publishers of technology books—and a fair number of smaller ebooksellers do. Powell’s Books, for example, has offered Adobe Digital Editions for a number of years and also offers Google eBooks in PDF format. Another example is Safari Books online, a digital library specializing in trade computer books from major publishers, which relies on PDF for delivering content.

You should only reasonably consider PDF as a principal format if you anticipate your audience to mostly use desktop or notebook computers (software programmers or engineers come to mind), or if you want your readers to be able to easily print your books while maintaining the layout exactly as you designed it.

The PDF format favors the following types of ebooks:

• Documents that your readers will likely want to print

• eZines, where the fidelity of the magazine page layout must be maintained

• Marketing collateral and data sheets that need to reach the widest possible audience (basically anyone with Adobe Acrobat Reader installed)

• Corporate reports and other documents that place high priority on presentation

The PDF format is less well suited for the following types of ebooks:

• Novels, short story anthologies, or other works of fiction that people primarily read for pleasure (reading longer works on desktop or notebook computers is generally a chore)

• Books that you would like to reach the widest possible audience through ebookstores such as Amazon.com or Barnes & Noble