China is gradually relaxing controls in many areas of life but Beijing keeps a tight grip on technology and access to media. These eight items are still off limits.
Change is afoot in China. Its leaders have promised a decisive role for markets in the huge economy, and a litany of economic reforms are underway. But in many areas, there's still a long way to go.
The social media platform can't be accessed from within the so-called Great Firewall of China, a censorship project operated for more than a decade by the Communist Party.
Thousands of websites cannot be viewed inside China either, but social media platforms draw special attention from censors.
Analysts say Beijing was particularly unnerved by the role social media played in the Arab Spring and the 2009 Green Revolution in Iran, leading to a blackout for the service.