China's restrictions on what its people can and cannot see online are some of the toughest and most controversial in the world.
Just how tough was exposed in 2008, when Western journalists at the Beijing Olympics found themselves unable to access a number of key sites.
Meanwhile internet giant Google has announced it will no longer work with the country.
But why is China so restrictive? How does it achieve such a level of control?
BBC World Service attempts to look beyond the great firewall of China.
Around The Firewall will be broadcast on 19 March 2010 as part of BBC World Service's SuperPower season.