nofollow is an HTML attribute value used to instruct some search engines that a hyperlink should not influence the link target’s ranking in the search engine’s index. It is intended to reduce the effectiveness of certain types of search engine spam, thereby improving the quality of search engine results and preventing spamdexing from occurring. The concept for the specification of the attribute value nofollow was designed by Google’s head of webspam team Matt Cutts and Jason Shellen from Blogger.com in 2005. The nofollow attribute value is not meant for blocking access to content, or for preventing content to be indexed by search engines. The proper methods for blocking search engine spiders to access content on a website or for preventing them to include the content of a page in their index are the Robots Exclusion Standard (robots.txt) for blocking access and on-page Meta Elements that are designed to specify on an individual page level what a search engine spider should or should not do with the content of the crawled page. Google announced in early 2005 that hyperlinks with rel=”nofollow” attribute would not influence the link target’s PageRank. In addition, the Yahoo, and Bing search engines also respect this attribute.