Date: How Recently Was the Page Published or Updated?
The 'currency' or 'freshness' of the information may be vital to your search. If you are looking for statistics, news about terrorism, or current scientific research, information published in 2007 may not be as reliable as data from 2015.
On the other hand, if you are not seeking time sensitive information, the date of publication may not be as important when determining credibility.
Remember: much of the time information on the Web is never updated after it is published. The information could be fresh or it could be stale. It is up to the searcher to decide if the date of publication is an important element in the search.
Determining when a web page was created or updated
Best: Find a copyright date that reveals the year the page was posted. This date is usually at the bottom of the page.
Second Best: Sometimes the page content will include dates, or references to dated materials. In the absence of copyright dates, these 'content dates' may be the best indicator of currency.
Third Choice: A date that is associated with a revision may have to do if there are no other dates available. Look at the bottom of a web page to see if the author has indicated when the page was last updated. Authors and webmasters typically put copyright, revision and update information at the bottom of the page.
What does 'updated' really mean?
Many Web page authors display the date when a page has been updated. This gives the searcher some idea of how fresh or current the information is. However an update may be as simple as a font change, a spelling fix, or the addition of a new link. It cannot be assumed, based on a modification date alone, that the content of the page has been significantly revised. The date is just one element in the evaluation of a Web resource.
Technical Methods to detect the date of a Web page
Some Web pages have no obvious date: no copyright, revision or timestamp. In such cases, finding publication information requires investigative searching to determine publication date information.
There are technical methods to help you find out the date that the page was last changed on the server. When you can't find copyright, revision, or update information, these methods can be useful. However, it is important to understand that the modification date will change when even a minor tweak is made on the page.
Finding Modification Dates using Metadata
Copy and paste the following code snippet into the omnibox to retrieve Last Modified information for any .htm or .html Web page:
If used on another type of Web page (e.g, .asp or .php or .pdf, etc.) the information will appear to be very recent--the time when the search was conducted. It doesn't mean the page was recently modified--it is simply the time the command was executed.
Other methods for finding the last modified date of a static Web page include:
- Browser tools: For example, using Firefox, right click on a page to be investigated and select View Page Info. The Last Modified information is display in an alert box. If you are using Firefox, try it on this page.
- The Metadata Search Wizard on this site includes ways to retrieve a variety of HTTP header information for any page, including Last Modified data (if provided).
Demonstration using the Digital Library Research page
When this demonstration was conducted (Aug. 27, 2015), at the bottom of the page was a statement that the page was last updated on April 29, 2002. Thirteen years is a long time ago--how reliable is this information? Entering the page URL in the Metadata Wizard retrieved a more recent date: May 9, 2013. So the page content IS more recent than 2002. But it's impossible from this alone to tell what is different than 2002.
An additional step is to look up archived copies of the page. Using the Wayback Machine on Archive.org it is possible to see the page as it looked on April 1, 2002. Comparing the two pages, the page hasn't changed substantially in 13 years. This raises a concern about the freshness of the information. In fact, a number of the links on the page are dead.
Technical methods of determining publication date are useful, but not as accurate as a printed copyright date. If the content contains a credible date, it may also be a better choice than this server modification method.
Web 2.0 and Dates
The Read-Write Web, while authorship can really be questionable, has distinct advantages over static Web pages when it comes to pinning down publication dates. Whenever someone posts material or a comment, a timestamp is created and printed.
Example: Google Blog. The dates were not put there by the authors but by the authoring software.
Finally, if a .pdf, .doc or other type of file is lacking a printed date, it is possible to check metadata by looking at page Properties.
Example: How digital tools prepare students for the 21st Century. This PDF doesn't display an obvious publication date. To find the metadata, download  the document from the Web and open it in Acrobat Reader or Pro (it doesn't need to be saved). From the File menu, open Properties. The created and modified dates are both displayed: March 30, 2009.
Authored by Lora K. Kaisler and Dennis O'Connor | revised 2015 by Carl Heine