nofollow is a value that can be assigned to the rel attribute of an HTML a element to instruct some search engines that a hyperlink should not influence the link target's ranking in the search engine's index. It is intended to reduce the effectiveness of certain types of search engine spam, thereby improving the quality of search engine results and preventing spamdexing from occurring.
Concept and specification
The concept for the specification of the attribute value nofollow was designed by Google's head of webspam team Matt Cutts and Jason Shellen from Blogger.com in 2005.
The nofollow value was originally suggested to stop comment spam in blogs. Believing that comment spam affected the entire blogging community, in early 2005 Google's Matt Cutts and Blogger's Jason Shellen proposed the value to address the problem.
The specification for nofollow is copyrighted 2005-2007 by the authors and subject to a royalty free patent policy, e.g. per the W3C Patent Policy 20040205] and IETF RFC 3667 & RFC 3668. The authors intend to submit this specification to a standards body with a liberal copyright/licensing policy such as the GMPG, IETF, and/or W3C.
<a href="http://www.example.com/" rel="nofollow">Link text</a>