How do I find out when a web page was written?

It's surprisingly difficult to tell with certainty when a web page was written. There are some clues we can gather that might help - a little.

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How do I find out what date a website or any thing on Google is written. Many times I look at Google to find websites but can never find out when a particular website is written.

In an absolute sense: you don’t. Surprising as it might seem, that kind of information actually doesn’t exist. There’s no place, no standard, no way to absolutely, positively say that this web page was written on this or that date.

The date that much of the information on the internet was written often doesn’t factor in to its value. But there are also times when knowing whether a page is a month, a year or a decade old can have a dramatic impact on its relevance.

While not absolute, and not 100% reliable, there are often clues we can use to determine just how old a page might be.

Let’s look at what some of those are.

Definitions

First, I need to be clear that Google really has nothing to do with this. Google is only a way for you to find web sites and web pages, and doesn’t really factor into the “when was it written” question. So I’m not going to be talking explicitly about Google – or any search engine – at all.

Second, what we really care about here are not web sites, but web pages. A site is a collection of web pages like, say, https://askleo.com. It may have a creation date 1, but in reality what we typically care about is the recency of a particular web page, like this one you’re looking at now.

The best source: the page itself

As silly as it sounds, the most authoritative source for when a web page was written is the page itself. By this I mean that many pages include an “updated” or “posted” date somewhere on the page. Even here on Ask Leo! you’ll see dates on all the articles:

Article Publication Dates

In this example, you’ll see two dates listed. I place the most current “posted” date near the bottom of the article, below the related links and above the tags.

The second is a reflection of the fact this the article had a major rewrite. So I choose to place the date of the rewrite as the posted date, and then include an explanatory statement about the rewrite, including its original date, above the related links.

There are, unfortunately, a bunch of problems with this.

  • I could lie. There’s nothing that forces these dates to be accurate.
  • There’s no standard location. Look above or below the main content of web pages, or perhaps in the web-page footer, for the most common locations.
  • The date may not be listed at all.

But in general, if the site takes the time to post a date with their content, that’s where I’d look.

HTTP Headers

What most people want is some kind of magic date information about when the web page was written that’s somehow within the page information. We figure it must be there, and we just can’t see it.

Well, there is always a ‘date returned’, but it’s not the date we want. When an HTTP request returns a web page, the date the response was generated is included. This is not the date of the page – it’s (roughly) the date you requested the page.

Not helpful.

There is sometimes an additional date returned called “Last Modified”, which is intended to reflect the date that the page being requested was last altered.

HTTP Headers

“Header” information returned with a web page. Note that the “Last-Modified” time is effectively useless to determine when the web page was written.

Once again, there are several problems with this approach:

  • It’s not required, and often is simply incorrect. In fact, in researching this issue, I note that my server does not send accurate Last Modified information when you fetch a page.
  • There’s no standard as to exactly what it means.
  • If it’s set at all, it typically means the last date (and time) that the file you’re accessing was altered, which can often have no relationship to when the content was written. For example, a page is “altered” every time someone leaves a comment. That is completely unrelated to when the article itself was written.
  • It could lie.

So the closest technological resources we have are woefully inadequate.

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History

OK, I lied: I’ll mention Google one more time.

Google, and all other search engines like it, could track historical changes to pages as they periodically spider the internet. If  a page appears one week, and the next week it changes, it seems like search engine spiders could track this activity.

To the best of my knowledge, they do not. If they do, they don’t typically make the information available.

The Internet Archive, on the other hand, does exactly that.

Using the Internet Archive’s “Wayback Machine”, I can actually view web pages “as they were” at some point in the past, assuming the Internet Archive had spidered and captured that web page on that date.

Sadly, the Internet Archive also has some serious limitations.

  • It’s spotty – within a site, not all pages on that site may be included.
  • It’s spotty – not all sites are included. In fact, webmasters can actually request that they not be included.
  • It’s spotty – not all dates are included. The Internet Archive’s spider checks “periodically” at what appears to be a rate of every few weeks. Changes occurring faster than that are not captured.
  • It can’t track all types of changes. A page moved from one domain to another (as I have been doing, moving articles from ask-leo.com to askleo.com – two different domains) will appear to be completely unrelated to one another in the archive.
  • It may not be current. The Archive states that it may take up to six months for pages to appear.

Even with all those limitations, it can be a useful piece of data for researching when, approximately, a web page changed.

If it’s in the Archive, of course.

The reason archiving of this sort is so challenging is simply the sheer quantity of data involved. An ideal archive would keep an entire copy of the entire World Wide Web every so often – and that’s more data than can be reasonably managed.

Apparently it’s timeless

Combining these approaches can often get you interesting information, but as we’ve seen, each approach has some serious limitations.

In the end, the answer remains “No”. There’s no definitive way to determine when a web page was written.

This is an update to an article originally posted : July 8, 2010
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Footnotes and references

1: 2003. Or, depending on what you mean, it could be sometime shortly thereafter, when askleo.pugetsoundsoftware.com became ask-leo.com. Or 2013, when ask-leo.com became askleo.com. Or 2014, when http://askleo.com became https://askleo.com. Even before we begin, things get confusing.

Comments

  1. Irving Stein

    this may work:

    javasc#ipt:alert(document.lastModified)

    Just copy and paste the line above in your address bar and
    hit your ENTER key – and you’ll know the date and time the page
    you’re viewing was last updated!
    Please comment on this
    Irv

    Which, as stated in the article, may well have nothing to do with what was written on the page. Pages get “updated” for random things and reasons. Example: some sites update the copyright notice every January 1 – so then the last modified changes even though the content did not. That’s just an example; there are many reasons that pages could be “modified” without content changing.

    Leo
    14-Jul-2010

  2. James

    Right, Irving, that was the first thing that popped into my head. But, what you have to remember is if that webpage is generated differently each time, it will give you a time that doesn’t seem right. For example, try that line on http://www.google.com . It will probably return a time a few seconds before you checked.

  3. Mike

    While knowing when a page was written may be important, sometimes the date you read it is just as critical. Specifically, citations for papers and articles often call for an article’s retrieval or access date more often than the publication date. But sometimes both, if they’re available.

  4. Gabe

    Thanks for dating your articles, Leo. I consider it an integral part of a professional article. It’s always very frustrating when you think you’re reading something very current until it references a “current event” that happened many years ago. I’ve even seen this on some news sites.

  5. Coly Moore

    I completely missed the date at the end of each of your articles. Well done! I do wish there were more like you (but of course Ask Leo is inimitable!).

  6. span

    This will work in most cases – On the page in question, type this in the address bar..

    Javascript:document.lastModified

    Hit RETURN and look in upper left of screen

    To get back to the page, click Refresh or Reload, whichever per your browser. BACK doesn’t do it.

    If the date is current, the time-stamp may be off due to time zone’s origin.

  7. Tamie

    Actually the date written can be important depending on the person’s reason for looking. I’m part of a writing group, and I just found this linked on my FaceBook feed: http://the-digital-reader.com/2015/03/03/scammers-now-trolling-indie-authors-with-bogus-dmca-noticest/
    I’m also a Computer Science major and it really bugs me that there is no easy way to prove how old a file/post really is. I came across your blog post in the process of trying to find out if there WAS such a solution.

    Now, I’m not so paranoid that I expect to be stolen from (but not so naive that I’ll rule it out), but the fact is, it is very easy to put in a fake date on your blog post, or to change the clock on your computer to back date a file, and that makes it all too easy to make the thief in these cases look like the victim.
    As you said: “I could lie. There’s nothing that forces these dates to be accurate.” And there is nothing that proves them to be false, either… and there I times I think that there really needs to be.

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