China has a policy of internet censorship and, because of this, almost 3000 websites are blocked on the country's mainland.
Hong Kong and Macau are special administrative regions of China where most Chinese laws, including internet censorship, do not apply.
Some examples of the types of websites that are blocked in China:
Political and activist websites hosted in other countries are blocked by mainland China. For example, Amnesty International's website is blocked.
Pornographic websites are very difficult to access in China.
Search websites / engines
Search engines like Google and Yahoo are banned.
Bing.com, WordPress, Vimeo and SoundCloud are all blocked.
Twitter, Facebook and YouTube are all blocked.
News reporting websites and NGOs
NGO sites like Reporters without Borders and Wikileaks can not be accessed from within mainland China. The same applies for news outlets like the Norwegian Broadcasting Corporation and SBS Radio.