nofollow 147
Interpretation by the individual search engines
While all engines that use the nofollow value exclude links that use it from their ranking calculation, the details
about the exact interpretation of it vary from search engine to search engine.[7][8]- Google states that their engine takes "nofollow" literally and does not "follow" the link at all. However,
experiments conducted by SEOs show conflicting results. These studies reveal that Google does follow the link,
but it does not index the linked-to page, unless it was in Google's index already for other reasons (such as other,
non-nofollow links that point to the page).[8][9] - Yahoo! "follows it", but excludes it from their ranking calculation.
- Bing respects "nofollow" as regards not counting the link in their ranking, but it is not proven whether or not Bing
follows the link. - Ask.com also respects the attribute.[10]
rel="nofollow" Action Google Yahoo! Bing Ask.com
Uses the link for ranking No No No?
Follows the link No Yes? No
Indexes the "linked to" page No Yes No No
Shows the existence of the link Only for a previously indexed page Yes Yes Yes
In results pages for anchor text Only for a previously indexed page Yes Only for a previously indexed page YesUse by weblog software
Many weblog software packages mark reader-submitted links this way[11] by default (often with no option to disable
it, except for modification of the software's code).
More sophisticated server software could spare the nofollow for links submitted by trusted users like those registered
for a long time, on a whitelist, or with an acceptable karma level. Some server software adds rel="nofollow"
to pages that have been recently edited but omits it from stable pages, under the theory that stable pages will have
had offending links removed by human editors.
The widely used blogging platform WordPress versions 1.5 and above automatically assign the nofollow
attribute to all user-submitted links (comment data, commenter URI, etc.).[12] However, there are several free plugins
available that automatically remove the nofollow attribute value.[13]Use on other websites
MediaWiki software, which powers Wikipedia, was equipped with nofollow support soon after initial announcement
in 2005. The option was enabled on most Wikipedias. One of the prominent exceptions was the English Wikipedia.
Initially, after a discussion, it was decided not to use rel="nofollow" in articles and to use a URL blacklist
instead. In this way, English Wikipedia contributed to the scores of the pages it linked to, and expected editors to
link to relevant pages.
In May 2006, a patch to MediaWiki software allowed to enable nofollow selectively in namespaces. This
functionality was used on pages that are not considered to be part of the actual encyclopedia, such as discussion
pages and resources for editors.[14] Following increasing spam problems and a within-Foundation request from
founder Jimmy Wales, rel="nofollow" was added to article-space links in January 2007.[15][16] However, the
various interwiki templates and shortcuts that link to other Wikimedia Foundation projects and many external wikis
such as Wikia are not affected by this policy.
Other websites like Slashdot, with high user participation, add rel="nofollow" only for potentially
misbehaving users. Potential spammers posing as users can be determined through various heuristics like age of