Definition and working principle of nofollow attribute

The rel = nofollow (which means do not follow) is added to a link (HTML tag) to indicate the search engines that this link should not be taken into account; in order not to increase the ranking in search engines, website pointed to the link. Wikipedia is an example of a site that uses the nofollow attribute to all outgoing links.

Here is a brief summary of nofollow attribute:

• Google does not follow the links to nofollow. The page pointed to by the link is not crawled or indexed. This link does not help the page it points to be better positioned in search results. Here is what is said by Google Blog : From Now On, When Google Sees The attribute (rel = “nofollow”) on hyperlinks, Those links Will Not Get Any Credit When We rank websites in search results.
• Search Yahoo! follows nofollow links. The page pointed to by the link is crawled and indexed. This link does not help the page it points to be better positioned in search results.

CMS (content Management System) platforms, like WordPress can use plugin to make all outgoing links nofollow. This is however, not recommended from our view. The administrator should himself handcraft and implement for each outgoing link; it might be tedious work, but it gives you the liberty to choose which one you would add nofollow and which not.

PHBb forum can not add rel=”nofollow” to any link by default, however forum administrators add this snippet to add nofollow to all outgoing links as well as make them to open in new window:

if ($user_cache[$poster_id]['posts'] < 75){$message = preg_replace('/(class="postlink")/','class="postlink" rel="nofollow" target="_blank"',$message);}

We must remind the readers, in PHBb  forums, it might be difficult to understand from the page’s source code, what bunch of attributes the Administrator of the forum is using.