If you are not involved in the search engine optimization community, January 21st, 2007 probably held no significance for you. However, if you are a search engine marketer or SEO, you probably remember January 21st as the day that Wikipedia died. To the untrained eye, Wikipedia is exactly the same today as it was six months ago. But, once you dig below the surface and take a look, you can see one difference that has had an impact on the world of search engine optimization: NOFOLLOW.
In the words of Matt Cutts, "rel="nofollow" attribute is an easy way for a web site to tell search engines that the web site can’t or doesn’t want to vouch for a link." Before January 21st, NOFOLLOW was mainly used for blog comments. This helped blog owners cut down on comment spam. NOFOLLOW was also used in some situations to denote a paid link, but this is a whole other controversy that will have to be saved for a different article.
The reason that Wikipedia’s adoption of NOFOLLOW on every single outgoing link caused such a stir is because many people viewed it as the most hypocritical decision that Wikipedia could have made. The reason that Wikipedia has become so popular and performs so well in the SERPs is that bloggers and web site owners commonly reference Wikipedia. When they do this, they provide a link back to Wikipedia. Every time that this process occurs, Wikipedia gains a little more popularity in the search engines. When Wikipedia decided to implement the NOFOLLOW tag, they are telling the search engines that although we reference a web site and may use content from it in our article, we do not want you to give it any credit. It is for this reason that many have started to view Wikipedia as a massive hypocrisy.
Although NOFOLLOW has probably cut down on the amount of spam Wikipedia has to combat, but as many others have stated, Wikipedia could have chosen a different method for fighting spam that did not punish quality web sites which deserve to be recognized by Wikipedia.