Google Penguin is a codename for a Google algorithm update that was first announced on April 24, 2012. The update is aimed at decreasing search engine rankings of websites that violate Google’s Webmaster Guidelines by using now declared black-hat SEO techniques involved in increasing artificially the ranking of a webpage by manipulating the number of links pointing to the page. Such tactics are commonly described as link schemes. According to Google's John Mueller, Google has announced all updates to the Penguin filter to the public.