nofollow

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.


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.

rel="nofollow"

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	Yes