Restricting the information which public communication systems may disseminate; usually one by an unstable or unpopular government.
Using religious reasons to edit, restrict or ban media productions. For example, Egypt banned the film The Message because it showed the shadow of the Prophet Muhammad's camel. In 1995 Islamic law was used to obtain a court injunction to stop the screening of the Egyptian film The Emigrant. In 1996, the Mexican administration imposed controls on gathering and disseminating information, in an attempt to hobble the Chiapas rebellion.
A CD issued by the Church of Scientology to its members contains a hidden filter designed to prevent them from using their Internet connection to read a wide range of websites, email and newsgroups which contain words that the Church deems harmful. The CoS censorware filters out a number of well-known critical sites, by making it impossible to connect to URLs with certain combinations of characters in them. Secondly, certain words are filtered out of the data stream and replaced with spaces, including the names of ex-members of the organization. One of the more interesting effects is word chopping, notably any configuration of "not" and "s" is deleted. This means that "not sure" becomes "ure", and that "not surprised" becomes "urprised."
News media have a perspective of their own which no government can afford to simply allow to predominate at the cost of other needed perspectives.
Most people are completely unaware of the extent of the daily hidden censorship of the media – every critical book, film, article and piece is submitted to libel lawyers for checking before publication or transmission. Most of those which carry any risk of leading to a libel writ are simply pulled and binned. If something is published and results in a writ, generally a humiliating apology or settlement is made to avoid the massive costs of a case.
Freedom of the media is a foundation of any regime which seeks responsible participation by its citizenry.