How do you remove a web page from the Google web search index after the content of the page has expired? Google has launched a new META tag called “unavailable_after” that webmasters can add to the particular webpage they want removed from the Google index after a specific date.
Google has announced the format in which the tag is to be used
<META NAME="GOOGLEBOT" CONTENT="unavailable_after: 31-Jul-2007 12:00:00 EST">
This simply tells Googlebot to remove this webpage from the Google search index after 31 July 2007 at 12.00 EST. Remember the format is as per RFC 850 format.
It is helpful if you have a temporary web page that will be removed at the end of the month. It is also useful if some pages are available free for a week, but after that you put them into an archive that users pay to access – this tag helps to remove search results for password protected pages.
This unavailable_after META tag is a welcome addition to the webmasters toolkit and will help site owners configure their expiring or pay for access content better and gives them more control on how their individual webpages are indexed by Google. At present this META tag is supported by Google only, but other search engines have a tendency to follow the Google way (as happened with the NOODP tag).
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