In the majority of SEO related blogs and forums one can see discussions regarding a non-standard attribute to the < a href >< /a > HTML tag. According to Wikipedia, and basically all other sources, the 'nofollow' attribute was designed by Google and bloggers.com, and has been accepted by all other major search engines.
Basically, the principle of the 'nofollow' tag is to instruct the search engine spider that the particular link to which the 'nofollow' attribute has been applied should have no added benefit in search engine rankings. This attribute was designed to help the "war" between Google (and other search engines) and spammers, who do everything possible in order to reach high positions in search engine rankings even if their pages are not of good quality.
Google says that all paid links should have a 'nofollow' attribute, as a person/business should not be able to buy a top place in search engine rankings by buying several links. Other links that should have the 'nofollow' attribute are links in comments on a blog system or guestbook, and links to external websites that are not relevant to the content of the particular web page (example link directories and link pages)
Most people are against the use of the 'nofollow' attribute, as it does hurt their rankings.
So what can be done? I always try to be positive when faced with a problem. In this case, I will do the same. This attribute offers also something quite powerful to the webmaster - the chance to control exactly where your 'pagerank' should go inside your website.
Let's assume you have a PR of 3 on your main page. Remember that PR is passed along to your internal pages through the link structure you have. Without the 'nofollow', you would have the PR passed to all the pages that are linked from your main page. These normally include the terms and conditions, legal stuff and more. Although important for your visitors, the search engine ranking of these pages is not considered important, and instead you want your 'products / services' pages to get a good ranking.
With the use of the 'nofollow' attribute, now you can decide where the pagerank will flow. Basically, you can stop 'wasting' Pagerank on irrelevant pages, and pass it on only to your most important pages that you want they get a good search engine ranking position.
Note: In this article we make reference to the Pagerank. Pagerank is a term used by Google, developed to give a rating to how much a web page is important, based on the amount and quality of other web pages that are linking to it. Although we are basing all the principles on how Google works, the same principles also apply to other search engines such as Yahoo and MSN. There are variations as how these search engines interpret the 'nofollow', but the concepts apply to all. (E.g. Google will literally not follow a link with the 'nofollow' attribute, whilst other search engines will still follow it, just that link will not be of any benefit to the ranking of the linked-to page.
Noel Grech is the Technical Director for [http://www.angmalta.net/]ANGMalta.net, a company offering [http://www.angmalta.net/services/design/design.php]complete web site solutions including website design, development, hosting and marketing.
