What is the NoFollow attribute?
The NoFollow attribute appeared in January 2005 in order to prevent comment spamming. In September, Google was recommending to use it for paid links as well. Indeed, some commenters were trying to fool Google’ ranking algorithm by integrating links with a lot of over-optimized keywords. Certain websites were over ranked in the search engine results because of the high amount of artificial links pointing toward them.
In fact, NoFollow is a value that can be assigned to the rel attribute of the HTML code to tell search engines not to count a link in the search engine’s index […]