nofollow 148
registered account and other factors. Slashdot also uses the poster's karma as a determinant in attaching a nofollow
tag to user submitted links.
Social bookmarking and photo sharing websites that use the rel="nofollow" tag for their outgoing links
include YouTube and Digg.com[17] (for most links); websites that don't use the rel="nofollow" tag include
Propeller.com (no longer an active website) (formerly Netscape.com), Yahoo! My Web 2.0, and Technorati Favs.[18]Repurpose
Paid links
Search engines have attempted to repurpose the nofollow attribute for something different. Google began suggesting
the use of nofollow also as a machine-readable disclosure for paid links, so that these links do not get credit in
search engines' results.
The growth of the link buying economy, where companies' entire business models are based on paid links that affect
search engine rankings,[19] caused the debate about the use of nofollow in combination with paid links to move
into the center of attention of the search engines, who started to take active steps against link buyers and sellers. This
triggered a very strong response from web masters.[20]Control internal PageRank flow
Search engine optimization professionals started using the nofollow attribute to control the flow of PageRank
within a website, but Google 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 a nofollow used for an internal link should work just like nofollow
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 have nofollow on internal links
pointing to them. Google employee Matt Cutts has provided indirect responses on the subject, but has never publicly
endorsed this point of view.[21]
The practice is controversial and has been challenged by some SEO professionals, including Shari Thurow[22] and
Adam Audette.[23] Site search proponents have pointed out that visitors do search for these types of pages, so using
nofollow 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 of nofollow on internal links have cited an inappropriate attribution to Matt Cutts[24]
(see Matt's clarifying comment, rebutting the attributed statement)[25] 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 employee Adam Lasnik[26] has advised webmasters that
there are better ways (e.g. click hierarchy) than nofollow to "sculpt a bit of PageRank", but that it is available and
"we're not going to frown upon it".
No reliable data has been published on the effectiveness or potential harm that use of nofollow on internal links
may provide. Unsubstantiated claims have been challenged throughout the debate and some early proponents of the
idea have subsequently cautioned people not to view the use of nofollow on internal links as a silver bullet or
quick-success solution.
More general consensus seems to favor the use of nofollow on internal links pointing to user-controlled pages
which may be subjected to spam link practices, including user profile pages, user comments, forum signatures and
posts, calendar entries, etc.