Internet censorship      

Internet pornography was outlawed in China by the People’s Republic of China effective 2002,
The Islamic state of Saudi Arabia bans all forms of pornography due to Islam’s opposition to pornography
Pornography is illegal in Vietnam and enforcement against it is strict.
In the United States, the Supreme Court held in 1969 that people could view whatever they wished in the privacy of their own homes.

source: http://en.wikipedia.org/wiki/Anti-pornography_movement

Internet censorship is control or suppression of the publishing or accessing of information on the Internet. The legal issues are similar to offline censorship.

One difference is that national borders are more permeable online: residents of a country that bans certain information can find it on websites hosted outside the country. A government can try to prevent its citizens from viewing these even if it has no control over the websites themselves. Filtering can be based on a blacklist or be dynamic. In the case of a blacklist, that list is usually not published. The list may be produced manually or automatically.

Source: http://en.wikipedia.org/wiki/Internet_censorship

Content-control software

Content-control software, also known as censorware or web filtering software, is a term for software designed and optimized for controlling what content is permitted to a reader, especially when it is used to restrict material delivered over the Web. Content-control software determines what content will be available.

Read more: http://en.wikipedia.org/wiki/Content-control_software