Internal or external links that use the nofollow attribute are not followed by search engines, just as the name suggests. This means their targets will not be crawled. Nofollow links do not pass on any link power (also called Linkjuice), like the anchor text or PageRank, to their target website either. Links like these are consider to be devalued.
If we consider this purely and subjectively from a link building perspective, then such links are no use at all, as the “nofollow” will have stripped the link of both its worth and effect. A nofollow link does not have any immediate positive effects on the ranking of a website but it is also not seen as a negative signal.
Should we therefore avoid nofollow links at all costs?
No. Nofollow links are part of every backlink profile and will usually come about naturally. If you, for example, have a Wikipedia entry or if your website is being referred in Wikipedia, the backlink is a nofollow link – without exception. That is because every external link on Wikipedia has the nofollow attribute. The nofollow link from Wikipedia does not pass on any link power, but Google is still able to recognise that an authority (Wikipedia) links to your website. This signal, even with the nofollow link, should be interpreted positively.
- You can quickly spot an unnatural link profile because of a very low nofollow ratio.
Where do nofollow links come from?
Most nofollow links are from sources where there is a possibility of user-generated content (short UGC), like in forums, comment or on rating websites, for example, where they are used as a means of spam prevention.
If you never use a nofollow link you may actually be at risk
In their Webmaster Guidelines, Google explicitly showcases scenarios where links have to be tagged with NOFOLLOW. If you do not follow this guideline, there is a possibility that you will be sanctioned by Google with an algorithmic or manual penalty.
2020 update: Two new attributes must be considered.
User generated content and sponsored rel attributes must also now be considered as important signals for Google that will help it traverse a site’s links. Read more information about rel=ugc and other atrributes