NoFollow Link Attribute
In January of 2005, Google made the unprecedented move of actually working together with other crawlers, and they agreed! The result was the nofollow attribute for links. Many people continue to call it the "nofollow tag", the that terminology is incorrect.
The impetus behind this was twofold - first, it's common for people who are desperate for links to buy them, and for webmasters desperate for money to sell them. As a business transaction, this is no problem, but because MSN, Yahoo and Google all use links as a "voting" system it caused a lot of issues, since these are not votes of confidence, but rather advertsing links, and therefore work against the idea of using backlinks to assign credibility and authority to sites.
Further, there are a lot of blogs out on the web that were started, then abandoned by their owners. Spammers have taken to adding links to their sites to the comments areas of these blogs, further messing up the relevancy algorithms of the search engines.
Finally, sometimes you may want to link to something you find objectionable, in order to shine a light on it. A link to a racist site from an anti-racist one, for example. The LAST thing you may want to do by this is to tell a search engine that you approve of, and vote for, the site this link leads to, and yet that's how link analysis works.
As a result, Google, MSN and Yahoo have agreed upon a new attribute - the nofollow tag. This allows a website owner to set a link as "untrusted" or something similar. Each engine will treat the attribute within it's own results in it's own way (they may or may not spider it, they may or may not add link weight to it, etc).
Will this tag get rid of spam? No. But it's yet another tool in the webmaster's and SEO's toolkit.
How do I tell Googlebot not to crawl a single outgoing link on a page?
Meta tags can exclude all outgoing links on a page, but you can also instruct Googlebot not to crawl individual links by adding rel="nofollow" to a hyperlink. When Google sees the attribute rel="nofollow" on hyperlinks, those links won't get any credit when we rank websites in our search results. For example a link,
<a href=http://www.example.com/>This is a great link!</a>
could be replaced with
<a href=http://www.example.com/ rel="nofollow">I can't vouch for this link</a>.
The usage is quite simple - the tag looks like this:
<a href=http://www.untrustedsite.com/ rel="nofollow">Untrusted SIte</a>
If you use FrontPage 2003 or before (as well as many other WYSIWYG editors, you must add the tag in manually in code view - there is no "right click" option (since the tag did not exist when they were created).
Ask does not intend to support this tag in the near future, since their link measuring algorithm is not as susceptible to manipulation as the other 3 search engines. But it certainly will not break links in any way. In short, if it makes sense to use the nofollow tag, then you should do so. Currently, there is no known downside to it, other than the fact that the person buying the link on your site may have been counting on the link weight and may be upset that you have deprived them of it.
For linking to sites you hate, it's great. For commercial links, there are ongoing arguments about the ethics and responsibilities of website owners. On the one hand, if you add a whole bunch of links that are not related to your site without nofollows on them, you may harm your own relevancy score. If you do add the tag, those who paid you or traded links with you would likely get upset.
Finally, if spammers know that their links are not going to count, you may find they will stop trying to add them. The problem is that since this type of spam is done on a non-personal, mass amount, it's not likely to make much of a difference in the number of attempts - just in the effect on the spam itself.
Use it wisely and carefully, and be aware of what you are saying when you do.
Rule of thumb: If you want to restrict robots from entire websites and directories, use the robots.txt file. If you want to restrict robots from a single page, use the robots metatag. If you are looking to restrict the spidering of a single link, you would use the link "nofollow" attribute.
|Websites or Directories||robots.txt|
|Single Pages||robots metatag|
|Single Links||nofollow attribute|