Internet Filters and Parental Control Software

   Internet filters and parental control software are terms describing software designed to restrict or control the content a reader is authorized to access, especially when utilized to restrict material delivered over the Internet. Content-control software determines what content will be available or what content will be blocked.

     A government can attempt to apply them nationwide or they can, for example, be applied by an ISP to its clients, by an employer to its personnel, by a school to its students, by a library to its visitors, by a parent to a child's computer, or by an individual user to his or her computer. The motive is often to prevent access to content which the computer's owner(s) or other authorities may consider objectionable.

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