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Duff Johnson

A veteran of the electronic document space, Duff Johnson is an independent consultant, Executive Director of the PDF Association and ISO Project co-Leader (and US TAG chair) for ISO 32000 and ISO 14289.
More contributions
Participating in the PDF Techniques Accessibility Summit

The PDF Techniques Accessibility Summit’s objective is to establish a broad-based understanding of how PDF files should be tagged for accessibilty. It’s an opportunity to focus on establishing a common set of examples of accessible PDF content, and identify best-practice when tagging difficult cases.

Members supporting PDF features!

The typical adoption curve for PDF technologies until approximately 2007 tended to track with that of the original PDF developer. Since then the marketplace has shifted; it’s no longer clear that Adobe drivesPDF feature support worldwide. Accordingly, we are happy to report that adoption of PDF 2.0 continues apace, with new vendors announcing their support every month.

Modernizing PDF Techniques for Accessibility

The PDF Techniques Accessibility Summit will identify best-practices in tagging various cases in PDF documents. Questions to be addressed will likely include: the legal ways to tag a nested list, the correct way to caption multiple images, the appropriate way to organize content within headings.

Refried PDF

My hospital emailed me a medical records release form as a PDF. They told me to print it, fill it, sign it, scan it and return it to the medical records department, in that order. In 2018? To get the form via email (i.e., electronically), yet be asked to print it? Did the last 20 years just… not mean anything! So I thought I’d be clever. I’d fill it first, THEN print it. Or better yet, never print it, but sign it anyhow, and return it along with a note making the case for improving their workflow. The story continues…

Slides and video recordings of PDF Days Europe 2018

You missed the PDF Days Europe 2018? Never mind! Here you can find the slides and video recordings of all 32 stunning sessions!

Have we passed ‘peak PDF’?

Graph shows "pdf" at "100" in September, 2015.Measuring mindshare by counting queries to search engines has its limits. When users search for “pdf” they probably don’t really care about the file’s format. Instead, we can infer that they are probably looking for something related to a “document”. Or… maybe they are just looking for a hacked version of an ebook.

Regardless of the reason, when users add “pdf” to a query it means that they are thinking about something that’s enabling them in some way that a web page isn’t.

And yet, in 2018, a web-page is an ever-more-dynamic experience. But are web pages really “documents”? In principle; yes, but in practice, when it has to be durable, reliable and portable… those things are still PDF files.

Some speculate that documents (or at least ideas about documents) are changing in profound ways.

Perhaps users will cease to care about self-contained ground-truth and accept that web-pages – the experience of which may vary with device, browser, CSS, bandwidth, server availability, etc. – are all they need?

People are already doing this. From banking to airline tickets to newspapers, users are happy with web technology, and accept its dependencies. And why not? The core web technologies (HTML, CSS, JavaScript) plus interchange formats such as JSON are extremely good at what they do.

But web technology can’t do everything. The idea of documents (reliable, self-contained and portable content) persists, and the technology of documents remains PDF.

That’s why, heedless of the expanding power of web technologies, PDF applications and usage continues to grow; its ecosystem ever larger and more vibrant with each year.

Self-contained: there is no substitute

Although the web is becoming ever-more capable, it offers no true replacement for traditional conceptions of documents. From academic papers to tax records, from business deals to bank-statements, a “document” remains something you could rely on when offline, or in 50 years time.

Like its cellulose ancestor, it might come from any source. It must be useable in any context. To put it in a single (hyphenated) word, it must be self-contained.

But the web doesn’t do “self-contained”. Wiser web folk accept this; they know that users demand portable documents, and that portability is not a trick the web does well. This is why browsers continue to steadily (albeit incrementally) improve their PDF support.

How do we gain insight into how users’ views of documents are shifting without spending egregious sums on dubious market-research?

One increasingly interesting source is Google Trends. This service aggregates Google’s search data to produce a metric describing search term popularity (relative to itself) over time. Here’s a great article about how Google Trends works.

Examining “PDF” in Google Trends

To help demonstrate the potential for marketplace insights from Google Trends, the balance of this article is devoted to a series of diagrams (all of which are static – visit Google Trends to run your own searches) conducted October 26-29, 2018.

The big picture

Although the curve is flattening, worldwide searches for “pdf” continue to grow in popularity, indicating that the popular appetite for documents remains healthy. Users may be banking online, but searches for documents continue to increase.

When we start to look more closely, however, some interesting questions arise.

Before iPhone / After iPhone

Here are worldwide Trends results for “PDF” from January 2004 (the earliest date available) until June 2007 (the month Apple introduced the iPhone):

Here’s “PDF” from July 2007 – October 2018:

Few would have guessed that the introduction of the iPhone would correlate with an increase in PDF’s popularity. And yet, it seems, as more people access online resources, even from smaller devices, the demand for pdf documents increased relative to other searches. As the graph makes clear, since 2007, searches for “pdf” have increased 3x relative to all other searches!

Work vs. play: annual cycles for “PDF” searches are changing

You may have noticed that the pre-iPhone plot is fairly smooth while the post-iPhone plot is considerably more jagged.

To make this change clearer, let’s break it down further: 2004-2007 vs. 2007-20013 and 2013-2018:

Notice the timing of the peaks and valleys in the most recent plot. They align with December and July of each year. What does this tell us? Unfortunately, all this can tell us for sure is that worldwide searches for “pdf” are becoming increasingly correlated with holiday cycles in the western world.

Possible explanations include:

  • PDF’s scope is narrowing to business
  • PDF applications in business are expanding relative to applications elsewhere
  • PDF’s appeal outside the west is declining
  • There’s a surge in users hunting hacked ebooks
  • Many other possibilities!


PDF is a globally-accepted format, everyone uses the same string. We know that interest in pdf continues to grow worldwide, but one obvious question is: where are searches for “pdf” increasing relative to all web-searches, and where are they not?

In the United States, for example, it’s possible that we may have already hit “peak PDF” with the highest proportion of searches for “pdf” occurring in September, 2015:

On the other hand, PDF’s popularity in the leading geographical area for technology in the United States, California’s Bay Area, is still growing:

And the same is true in the nation’s capital. PDF is in no danger here!

Irrespective of its feelings about PDF, Ontario’s provincial government isn’t making much headway in replacing it…

Unlike the US, German interest in pdf has remained rather steady since 2004, but there are some interesting peaks:

… it turns out the peaks are associated with the World Cup!


Does search-term popularity allows us to compare interest in various technologies? Of course, it’s unfair to compare a general-purpose electronic document format such as PDF to a publishing format like EPUB, but it is nonetheless interesting as a gauge of where the wind is blowing.

Related queries

What are the terms that users search for alongside “pdf”? Here too, there’s a lot to look at and think about.

Tags: Trends
Categories: Perspective