Common value for a HTML robots meta tag.
The HTML meta robots tag can be set to 'noindex' to indicate that spiders should avoid indexing this web page.
The noindex value is often used with transitory web pages (ie. will expire before they enter the search engine), printer/mobile-friendly versions of existing indexed web pages, or to avoid the indexing of very large databases.
Not all search engine spiders pay attention to this tag.
