EPUB vs PDF – Who is the winner?

In the rapidly growing arena of electronic publications, there are two open-source contestants for the e-book market: EPUB and PDF.

A little background

The EPUB format, based on HTML/XHTML, is primarily used for the commercial book market. As the most widely used e-book format, it is supported by all major e-readers except Kindle (but that is about to change). The EPUB format is particularly well suited to mobile devices because it features reflowable text. This means that the text in an EPUB will reflow appropriately on a mobile device, no matter what its size. You can make the type larger or smaller, and the text will reflow appropriately. Text will not be cut off at the right margin, and you will not have to scroll horizontally to read the remainder of each line. 

The PDF format, on the other hand, is primarily used for business or technical documents. It was developed as a way to quickly convert documents designed for print (8½ by 11 or A4) to an online format. This means that when you access a PDF on a smartphone, the type is usually too small.  If you use older PDF readers, you often have to enlarge the PDF manually and then scroll horizontally to read it (which is annoying).

Undoubtedly, there’s a mashup occurring between the traditional markets for PDFs and EPUBs. PDFs, which were often relegated to the business and technical domain, are now being used for e-books. (Note that PDFs can be read with e-reader software and PDF-reader software.) Additionally, current PDF readers are being improved so that they can more easily reflow text and do all the good things that e-readers can do.

EPUBs, on the other hand, will certainly be spreading into the technical and business environments, once problems related to complex formatting are solved.

A summary

Here’s a table that summarizes the differences between PDFs and EPUBs (as of 9/6/2011):

Feature EPUB PDF (viewed with a PDF Reader)
Reflowable text EPUBs automatically reflow (and hyphenate) and are well suited for mobile devices.  PDFs are written in concrete – remember, they’re based on printed pages, typically 8½ by 11, and (with many PDF readers) they do not reflow when enlarged. This can make PDFs difficult to read on smaller mobile devices. Note: Adobe Reader X and a few other readers give users the ability to reflow text; however, this feature is typically not automatic.  
Change the font and specify a particular font size EPUBs can do this. PDFs cannot do this on many PDF readers.
Page turning To turn the pages of an EPUB, users swipe horizontally. To turn the pages of a PDF, users scroll vertically, and because of bottom page margins, there are typically larger gaps between pages.
Complex tables   With EPUBs, complex tables can be problematic, and content or coding often needs to be tweaked to make these types of tables work. With PDF, although complex tables may not require tweaking, they are often difficult to read on smaller devices and pose problems (horizontal scrolling) when enlarged.
Graphics On small mobile devices, graphics can be difficult to read in EPUBs. On small mobile devices, graphics can be difficult to read in PDFs.
Search Available with EPUBs. Available with PDFs.
Annotation  Available with EPUBs. Available with PDFs.
Copy text Available with EPUBs. Available with PDFs.
Audio and video   Available with EPUBs (depending on the e-reader). Available with PDFs.


The bottom line

As these two technologies invade each other’s spaces, it’s likely that they will borrow from each other’s feature set. In fact, it’s already happening, since the latest Adobe Reader can now reflow text. So stay tuned to see what happens as these two technologies morph and compete in the rapidly expanding, multifaceted world of e-books.

Note: Parts of this blog post are excerpted from Nad Rosenberg’s article, “What you need to know about e-books,” to be published in Intercom, a monthly publication of the Society for Technical Communication, in November 2011.

© 2011, TechWRITE, Inc.

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