Google has been involved in the censorship of certain sites in specific countries and regions. Until March 2010, Google adhered to the Internet censorship policies of China, enforced by filters colloquially known as "The Great Firewall of China". Google.cn search results were filtered to remove some information perceived to be harmful to the People's Republic of China (PRC). Google claimed that some censorship is necessary in order to keep the Chinese government from blocking Google entirely, as occurred in 2002. The company claims it did not plan to give the government information about users who search for blocked content, and will inform users that content has been restricted if they attempt to search for it. As of 2009, Google was the only major China-based search engine to explicitly "inform" the user when search results are blocked or hidden. As of December 2012, Google no longer informs the user of possible censorship for certain queries during search.