March 2, 2015 2

EPUB, the latest much-touted “replacement” for PDF as the world’s electronic document format, appears to have peaked, and is now in the process of returning to earth.
That is, according to Google Trends data as of March 2, 2015 (as captured in this screen-shot):
EPUB on Google Trends as of March, 2015. EPUB is significantly down from its peak in January 2014.
The internationally-standardized PDF format, however, continues to gain:
PDF on Google Trends
Notwithstanding IBM’s announcement at the beginning of 2014 that the company would be standardizing on EPUB, the company’s website is still awash in PDF files – over 874,000. the ebook format created by a consortium of publishers is limping, with consumers and the media complaining that the EPUB experience is inconsistent between devices, and plagued by DRM issues, among other concerns.
The reason for EPUB’s halting (if not negative) progress boils down to the same reasons why PDF is so successful, and continues to grow.
Unlike EPUB, PDF documents can contain high-quality, resolution-independent content from any source. Unlike EPUB, PDF technology includes all the basic features people expect in electronic documents, including the ability to add comments, redact text, use pages of differing sizes and orientations, navigate objects that span more than a single page, and more.
Once software vendors have added features to PDF viewers that allow for an EPUB-like experience we can expect to see the appeal of EPUB continue to fade. Given that the US federal government’s Access Board has dramatically raised the profile of accessible PDF, this sort of development will not be long in coming.
Unlike EPUB, PDF isn’t just a publication format, it’s a document format. It seems that people like their publications to have document features as well.