How accountable are web pages?

HTML iconDoes the world still run on paper documents? No… and yes.

To be sure, vast quantities of documents and data reside on servers. This material is accessed worldwide, millions of times per second, 24 hours a day. It’s typically delivered from web server to browser in HTML, the core language of the web.

We trust this content. HTML is used to deliver booking systems, online shopping, bank account status, sports scores, airline reservations and FaceBook, among many other things, with near-total reliability.

But when delivering a finished document – a bank statement, a signed contract, a disclosure form, an official notice, a formal report – HTML is less appropriate. PDF is preferred.

Most people never think about why they trust PDF for critical or accountable content any more than they think about plumbing when they turn a tap for some water.

What is it about PDF?

Why is PDF the format of choice for important communications, negotiated documents and formal records?

The reason is simple, and underlies the inherent difference between HTML and PDF:

  • HTML depends on a mixture of CSS, JavaScript and interpretation by web browser software for its appearance on the screen. If the server’s content changes or a different browser is used, the appearance can change.
  • PDF documents are fixed and self-contained. The software either works or doesn’t work, and there’s no dependance on a server. If the file is in your possession, no-one else can change its content or appearance.

The problem with web pages is impermanence, and not just because the way the document appears is up to the browser. You’re depending on a link to resources someone else owns and tends. Unlike a file on your own hard-drive or in your own cloud, the actual contents of HTML pages can change without notice.

It’s for this reason that when you need to prove something, or want to be certain that everyone sees the same thing, you use PDF.

PDF is forever. HTML depends on context.

Although HTML/CSS and JavaScript make the difference between plain-vanilla text and a web-page, they do not make something you can rely on regardless of software, operating system, location, connectivity… or trust.

When you need to hold a company, government agency or individual to account.. you choose PDF.

When you need to prove something… you choose PDF.

That’s why PDF is so vital to democracy.


  1. July 9, 2014 at 08:32

    Been a long time fan of yours Duff – up until Acrobat Pro XI, I would agree with you . But for records management qualities of “trustworthy” and “reliable”, the capability wrought in this version (probably from graphics professionals) to edit text and images /content editing – “fixed and self-contained” – ain’t necessarily so (unless I secure with password. Securing with a password negates my long term storage advantage. I could save as an image, but I could have done that by printing it out and scanning without OCR. If there is a capability in XI for immutability, I haven’t found it. Again, I love Acrobat, but flatteners/javascript are thwarted from my experience with this version.
    kind regards

  2. July 11, 2014 at 15:42

    A great comment, Susan, thanks.

    The truth is that absent a digital signature there never was any way to *guarantee* the absence of tampering with a PDF. The contents of unsecured PDF files have always been editable. This isn’t new with Acrobat XI, it’s just easier than before.

    I wasn’t trying to say that PDF files are tamper-proof. PDF pages are “fixed” in the sense that the layout does not change based on the viewing device, operating system or software.

    That said… even digital signatures aren’t a complete answer – without security in addition to the signature they may be subverted by software that ignores them. One need only look at Apple’s Preview, which destroys digital signatures, to see this fact in action, as I discussed in this post:

    The painful reality (and this is true of all file-formats, PDF and otherwise) is that chain-of-custody is the *only* way to completely and totally guarantee fidelity to an original. PDF – unlike HTML and other formats – fundamentally enables chain-of-custody due to the fact of being entirely self-contained.


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