The nofollow Link Attribute-SEO forums

The nofollow Link

The nofollowlink attribute is not new, but
 it is still a fairly popular topic in SEO forums
and blogs, and there still seems to be
confusion about the use of this link
 attribute. Inearly 2005, Google introduced
the nofollowlink attribute to
“prevent comment spam”
in blogs, message boards, and so forth.

If you’re a blogger or a blog reader, you’re
 painfully familiar with people who try to
raise their own websites’ search engine rankings
 by submitting linked blog comments
like “Visit my discount pharmaceuticals site.”
This is called comment spam, we don’t
like it either, and we’ve been testing a new
 tag that blocks it. From now on, when Google
sees the attribute rel=“nofollow” on hyperlinks,
those links won’t get any credit when
we rank websites in our search results that
 increase your blog traffic.
 This isn’t a negative vote for the site
 where the comment was posted; it’s just
a way to make sure that spammers get no
 benefit from abusing public areas like blog
comments, trackbacks, and referrer lists.

The major search engines support the
  nofollow attribute, but in different capacities.
Whereas Google will honor the attribute in
 its most conservative form—by not indexing
 or passing PageRank—other search engines
might index the link or even pass the
link juice.

A perfect example of the misuse of
the nofollow attribute is on pretty much
every page of Wikipedia. Wikipedia
indiscriminately uses nofollowon almost
 all outbound links,including .gov and .edu links.

If a regular link looked like the following:

<a href="">Great Site</a>

the link that should be “not followed”
 would be in this form:

<a href="" rel="nofollow" >
Great Site</a>