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.
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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:
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.
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.
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.
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.
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.