Internet censorship involves filtering what users can access online. Governments and corporations cite reasons like protecting families, national security, and traditional values. Censorship methods include DNS hijacking to redirect requests, blocking addresses or ports, and filtering web content. Countries like Iran censor political, news, and social media pages. Anti-censorship systems try to connect censored users securely and anonymously to the open internet using methods like HTTP proxies, CGI proxies, VPN tunneling, and more.