The Chinese government blocks Facebook and has since 2009.
Tencent, China’s largest tech company, just launched a multilingual version of its chat platform QQ on Facebook. QQ is the Chinese equivalent of Yahoo Messenger, circa 2003—only it has 800 million active users. And the version of QQ that Tencent made for Facebook isn’t much different: Its core function is pretty much the same as Facebook’s own chat function.
Wait. Why would anyone use an app in Facebook that does pretty much exactly the same thing as Facebook chat?
Because the Chinese government blocks Facebook and has since 2009. The QQ app makes it so Facebook users outside of China can chat with friends both inside and outside of the country without having to leave the Facebook screen.