The noindex value of an HTML robots meta tag requests that automated Internet bots avoid indexing a web page.
Also the interpretation of the noindex tag is sometimes slightly different from one search engine company to the next.
Possible values for the meta tag content are: "none", "all", "index", "noindex", "nofollow", and "follow".
Google's main indexing spider, Googlebot, is not known to recognize any of these techniques.
It is also unknown whether the attribute can be applied to tags other than