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nofollow is a setting on aweb pagehyperlink that directssearch engines not to use the link forpage ranking calculations. It is specified in the page as a type oflink relation; that is:<a rel="nofollow" ...>. Because search engines often calculate a site's importance according to the number of hyperlinks from other sites, thenofollow setting allows website authors to indicate that the presence of a link is not an endorsement of the target site's importance.
Thenofollow value was originally suggested to stop commentspam in blogs. Believing that comment spam affected the entireblogging community, in early 2005Google'sMatt Cutts andBlogger'sJason Shellen proposed the value to address the problem.[1][2]
The specification fornofollow is copyrighted 2005–07 by the authors and subject to a royalty-free patent policy, e.g. per theW3C Patent Policy 20040205,[3] andIETFRFC 3667 and3668.[2]
<ahref="http://www.example.com/"rel="nofollow">Link text</a>
Google announced in early 2005 that hyperlinks withrel="nofollow"[4] would not influence the link target'sPageRank.[5] In addition, the Yahoo and Bing search engines also respect this attribute value.[6]
On June 15, 2009, Google software engineerMatt Cutts announced on his blog that GoogleBot changed the way it treats nofollowed links, in order to prevent webmasters from using nofollow for PageRank sculpting. Prior to this, webmasters would place nofollow tags on some of their links in order to maximize the PageRank of the other pages. As a result of this change, the usage of nofollow leads to the evaporation of the pagerank of outgoing normal links as they started counting total links while calculating page rank. The new system divides page rank by the total number of outgoing links irrespective of nofollow or follow links, but passes the page rank only through follow or normal links. Cutts explained that if a page has 5 normal links and 5 nofollow outgoing links, the page rank will be divided by 10 links and one share is passed by 5 normal links.[7] However, as of March 1 2020, Google is treating the nofollow link attribute as a hint, rather than a directive, for crawling and indexing purposes.[8]
While all engines that use thenofollow 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.[9][10]
| rel="nofollow" Action | Yahoo! | Bing | Ask.com | Baidu | |
|---|---|---|---|---|---|
| Uses the link for ranking | No | 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 | — |
| Inresults pages for anchor text | Only for a previously indexed page | Yes | Only for a previously indexed page | Yes | — |
Many weblog software packages mark reader-submitted links this way[15] by default (often with no option to disable it, except for modification of the software's code).
More sophisticated server software could suppress the nofollow for links submitted bytrusted users like those registered for a long time, on awhitelist, or with an acceptablekarma level. Some server software addsrel="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 platformWordPress versions 1.5 and above automatically assign thenofollow attribute to all user-submitted links (comment data, commenter URI, etc.).[16] However, there are several free plugins available that automatically remove thenofollow attribute value.[17]
Social bookmarking and photo sharing websites that use therel="nofollow" tag for their outgoing links includeYouTube andDigg.com[18] (for most links); websites that don't use therel="nofollow" tag includeYahoo! My Web 2.0,Technorati Favs, andPropeller.com (no longer an active website).[19]
Search engine optimization professionals started using thenofollow attribute to control the flow of PageRank within a website, but Google has since corrected this error, and any link with a nofollow attribute decreases the PageRank that the page can pass on. This practice is known as "PageRank sculpting". This is an entirely different use than originally intended.nofollow was designed to control the flow of PageRank from one website to another. However, some SEOs have suggested that anofollow used for an internal link should work just likenofollow used for external links.
Several SEOs have suggested that pages such as "About Us", "Terms of Service", "Contact Us", and "Privacy Policy" pages are not important enough to earn PageRank, and so should havenofollow on internal links pointing to them. Google employeeMatt Cutts has provided indirect responses on the subject, but has never publicly endorsed this point of view.[20]
The practice is controversial and has been challenged by some SEO professionals, including Shari Thurow[21] and Adam Audette.[22] Site search proponents have pointed out that visitors do search for these types of pages, so usingnofollow on internal links pointing to them may make it difficult or impossible for visitors to find these pages in site searches powered by major search engines.
Although proponents of use ofnofollow on internal links have cited an inappropriate attribution to Matt Cutts[23] (see Matt's clarifying comment, rebutting the attributed statement)[24] as support for using the technique, Cutts himself never actually endorsed the idea. Several Google employees (including Matt Cutts) have urged Webmasters not to focus on manipulating internal PageRank. Google employeeAdam Lasnik[25] has advised webmasters that there are better ways (e.g.click hierarchy) thannofollow to "sculpt a bit of PageRank", but that it is available and "we're not going to frown upon it".
YouTube, a Google company, uses nofollow on a number of internal "help" and "share" links.[26]
On September 10, 2019, Google announced[27][28] two additional ways for webmasters to qualify the relationship of outbound hyperlinks. The attributerel="sponsored" may be used to denote links that are advertisements, sponsorships or other compensation agreements. The attributerel="ugc", standing for "User-generated content", may be used to denote content such as user-contributed comments and forum posts. Additionally, the attributes may be combined, such asrel="ugc sponsored", denoting a link that was both user-generated and sponsored. In 2019, WordPress announced plans to convert all blog comments into rel="ugc".[29]
These "hint" link attributes address some of the criticisms ofnofollow by allowing webmasters to denote outbound links that lack "the weight of a first-party endorsement", but are not necessarily spam.
