The Children's Internet Protection Act is a federal law enacted by Congress in December 2000 to address concerns about access to offensive content over the Internet on school and library computers.  Therefore, after 2000, library computers are required to be filtered. In general, children under 17 or 18 (depending on the library) years of age are required comply with filtering regulations.  Blocked content includes adult/sexually explicit materials, remote proxies, and violence.  For youger children, there are higher levels of filtering options available.  These options might filter contenct such as advertisements, spyware, chat, search engines, glamour and intimate apparel, sexual education, hosting sites, tasteless and offensive material, personals and dating, usenet news, phishing and fraud, web-based e-mail, shopping.  Adults over the age of 17 or 18 can chose to remove filters completely, so their right to access information is not violated. There are a variety of products available for filtering in libraries (see http://libraryfiltering.org/) one commonly used product is SurfControl.