Internet filtering is the screening of an incoming web page to determine whether some or all of it should not be displayed to the user. The filter checks the origin or content of a web page against a set of rules provided by company or person who has installed the web filter. The filter allows an enterprise or individual user to block out pages from web sites that are likely to include objectionable advertising, pornographic content, spyware, viruses, and other objectionable content.
Though filtering is allowed for some purposes, there are restrictions placed on filtering of contents on the net. In 1996 the United States enacted the Communications Decency Act, which severely restricted online speech that could potentially be seen by a minor – which, it was argued, was most of online speech. Free speech advocates, however, managed to have most of the act overturned by the courts. Opponents of Internet censorship argue that the free speech provisions of the First Amendment bars the government from any law or regulation that censors the Internet.