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I thought Google was more or less accurate at determining who posted a text first and who copied. However, when I use the "search tool: customized interval" the results are quite odd. I've found pages dating back to 2002 for a website I've had for only a couple of years.

So Google isn't accurate to find out who copied and who wrote the original. What is?

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If stackexchange.com was created in 2009 then how is this possible? hermeneutics.se is older than Stack Overflow!

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Did someone own the domain name before you? What is the page(s) you are comparing in Google? –  closetnoc Mar 18 at 1:08
    
I updated the question with SE data. The time stamps can't be accurate. –  Renan Mar 18 at 2:20
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Wow. I am not sure. I understand the mechanics of this normally, but what Google does is still a mystery. There is very little info on the net about how Google determines dates. We had a question regarding how Google determines modified dates just a while ago. I did some research and there is almost nothing. Still, I will look again. But it may take a couple of days. Keep in mind that CMS software and likely the SE code does not return create and modify dates like Apache would for HTML pages. And this may be the answer. –  closetnoc Mar 18 at 3:02
    
It doesn't have to be Google but I really want to know if my users are plagiarizing or being plagiarized. =/ –  Renan Mar 18 at 3:28
    
So far, it is looking like Google is not understanding the date format within the HTML but this is not conclusive. The source code of the first example page does not provide clear date clues to Google. Google (at least) looks or a date in this order: URL, title, body (content), meta tags, last modified date from HTTP response. A HEAD request returns create date and last modified date. As well, a GET with if-modified-since either returns the resource with a 200 Ok or returns a 304 Not Modified. The SE code may not be returning these and only URL, title, content, and meta tags are available. –  closetnoc Mar 18 at 5:15
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2 Answers 2

I researched the answer to this question this way: using Google since this is the example I have, how Google gets creation dates and modified dates, and date formats that Google recognizes. Please understand that this information does not exist on just a few pages and I had to ferret out the data from very many sources some of which do not seem to apply directly and piece it together. In some cases, the information is derived from several sources and not always quotable.

Google looks for page dates in this order; URL, title tag, body (content), meta-tags, HTTP response header at least as far as the Google search appliance is concerned. In other paragraphs in other documents, no order was documented, but the list was discussed and seemed to confirm the list. If you think about it, this mirrors the order that a search engine would; one - discover your page (link), and two - read your page from top to bottom (title, body, and meta-tag) with the exception of the meta-tag (small detail) and HTTP response header. Here is the list as far as the appliance is concerned: https://developers.google.com/search-appliance/documentation/68/admin_crawl/Preparing#docdaterule

Note: The inception date is the date that the page was first requested by Google. In the absence of a creation date, the inception date is used.

1] Any search engine can request a resource via a HTTP GET request and the web server returns the last modified date within the response header with the resource within the data packet.

2] Any search engine can request header information of a resource via a HTTP HEAD request and the web server returns the modified date within the response header without the resource within the data packet.

3] Any search engine can request if a resource has been modified since a certain date by requesting a resource with a HTTP GET with if-modified-since set to a date. If the resource has been modified since the date set, the web server responds with a 200 Ok response and returns the resource or if the resource has not been modified since the date set, the web server responds with a 304 Not Modified without returning the resource.

Google makes many requests using method #3 to save on bandwidth. You will see these in your web server log files.

Note: It is possible that a content management system (CMS) or other software cannot provide date appropriately within a response header.

These date examples also come from the Google appliance documentation but also exist in other places concerning general search. I took these details from the appliance documentation simply because it could be cut and pasted as a list where in other places it was not as neat.

4] Google looks for a date within the URL. It looks for the following formats; YYYMMDDHH - YYYY - YYYYMM.

5] Google looks for a date within the title tag. It looks for the following formats; YYYMMDDHH - YYYY - YYYYMM though I suspect other formats can be recognized. See below.

6] Google looks for a date within the body tag (content). It looks for the following formats; YYYMMDDHH - YYYYMMDD - YYYYMM - YYYY - DDMMYYYY - YYMMMDD - MMDDYYYY - YYMMDD - DDMMYY - MMDDYY though I suspect other formats can be recognized. See below.

Note: It is known that Google looks specifically for a date just under the first H1 tag. This is because blogs often put dates in this location.

7] Google looks for a meta-tag like this one. <meta http-equiv="last-modified" content="YYYY-MM-DD@hh:mm:ss TMZ" />

Google is also said to recognize the following date formats.

YYYY-M-D - YYYY.M.D - YYYY/M/D - M-D-YYYY - M.D.YYYY - M/D/YYYY - YY-MM-DD - YY.MM.DD - YY/MM/DD - WK, D MON, YR - WK, MON D, YR - D MON, YR - MON YYYY - MON D, YR - MON YY - YYYY-D-M - YYYY.D.M - YYYY/D/M - D-M-YYYY - D.M.YYYY - D/M/YYYY - DD-MM-YY - MM-DD-YY - DD/MM/YY - MM/DD/YY - YYYYMMDDHH - YYYYMMDD - YYYYMM - YYYY - DDMMYYYY - MMDDYYYY - YYMMDD - DDMMYY - MMDDYY

The research I found did not answer the question of time.

In the case of the examples cited, the pages do not provide date clues except for within a span tag which may be ignored. It is possible that the SE software / web server cannot return creation and modified dates within any response header.

Why and how Google derived these dates is a good question that may never be resolved. I will keep looking however.

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Do you have any reference for "Google looks for page dates in this order; URL, title tag, body (content), meta-tags, HTTP response header."? Do you have any number or statistic for this research?. If you could post references for what you posted here, it would be much better for all of us. –  PatomaS Mar 19 at 7:02
    
I appreciate your asking this. Much of what I found was in bits and pieces. The list was found in several places, but the order was found in documentation for the Google search appliance and seemed to be backed up in paragraphs in other places. I literally looked at several dozen documents that took quite a bit of time to find. I tried to be careful to say that I had to piece together the data from a variety of sources since there did not seem to be any direct info on this. I will edit the statement to make it clearer. –  closetnoc Mar 19 at 15:46
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If you want to see how old is a domain, search on Google for wayback machine. This site is what you're looking for: http://archive.org/web/.

If you want to detect plagiarism, this link will help you: http://copyscape.com/signup.php?pro=0&o=f

Also, search on Google for "plagiarism checker".

Hope I helped.

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With respect, you need to re-read the question. –  closetnoc Mar 18 at 15:07
    
The question is "How to tell how old a page is?" Please follow my link and you'll see that the answer is good. Thanks for reading this. –  Pascut Mar 18 at 15:46
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You are not reading the question. You are reading the title. The way back machine does not answer the question. –  closetnoc Mar 18 at 15:50
    
You're right, I've edited my question.. –  Pascut Mar 18 at 15:57
    
Wayback machine keeps track of the page in the domain. It's not useful to compare dates between specific pages. I'm looking for accurate means to tell which one was posted first. –  Renan Mar 18 at 17:25
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