Google has extended its support for Google Bot restriction by giving us web developers a new tool to stick in our belt. It was announced today on the Google Blog that you can now control access to your non-HTML files on your website with a simple header. The header
- INDEX|NOINDEX – Tells whether the page may be indexed or not
- FOLLOW|NOFOLLOW – Tells whether crawlers may follow links provided on the page or not
- ALL|NONE – ALL = INDEX, FOLLOW (default), NONE = NOINDEX, NOFOLLOW
- NOODP – tells search engines not to use page titles and descriptions from the ODP on their SERPs.
- NOYDIR – tells Yahoo! search not to use page titles and descriptions from the Yahoo! directory on the SERPs.
- NOARCHIVE – Google specific, used to prevent archiving (cached page copy)
- NOSNIPPET – Prevents Google from displaying text snippets for your page on the SERPs
- UNAVAILABLE_AFTER: RFC 850 formatted timestamp – Removes an URL from Google’s search index a day after the given date/time
So how can X-Robots-Tags help you better control the content that is indexed by Google? Well you can now tell the Google Bot that you do not want specific non-HTML documents like PDF, Word, and Image documents that you don’t want them cached on the Google Server or that a paper you have released on your website in PDF format should only be good until a specific date. So now you just need to force you server to include an addition X-Robots-Tag in the header which can be done with any of the modern languages and server, the header would look something like this:
Date: Tue, 31 Jul 2007 21:41:38 GMT Server: Apache/1.3.37 (Unix) PHP/4.4.4 X-Powered-By: PHP/4.4.4 X-Robots-Tag: index, noarchive, nosnippet Connection: close Transfer-Encoding: chunked Content-Type: application/pdf
You can do this with anything that can be served over HTTP now, so this is a huge boost for any of us control freaks that like to have our content easily organized and controlled on what is searchable on Google.