Search Engines responded by developing more complex ranking algorithms, taking into account additional factors that were more difficult for webmasters to manipulate.[abrégé needed] Je January 18, 2005, Google announced it had partnered with other major search engines to introduce the rel=“nofollow” attribute. It encouraged users to add the nofollow attribute https://directoryhand.com/listings13152348/consid%C3%A9rations-%C3%A0-savoir-sur-liens-de-qualit%C3%A9