The main function of Jingjing and Chacha is to intimidate,” a Shenzhen official told The Beijing Youth Daily. The newspaper article said the characters are there “to publicly remind all Netizens to be conscious of safe and healthy use of the Internet, self-regulate their online behavior and maintain harmonious Internet order together.” (Source)
I mentioned how you can experience censorship in China before. This video presents some of the facts about internet censorship around the world.
Internet Censorship (Wiki)