Because new sites are joining the Internet daily, and pornographic sites in particular change addresses frequently, services that use this black-list approach cannot restrict children's access as fast as the sites appear. A recent study showed that the best Web filters keep children from accessing only 10 of every 12 pornographic sites. Considering the millions of sites available, children and teens can still access thousands of sites that parents would consider inappropriate. Second, although these services offer some customization, they do not give parents the ability to control access based on their own values and children's needs but must rely on the judgment of the service provider. These providers use predefined rules to identify inappropriate sites and apply the rules to everyone who subscribes to the service.
Parents have limited control over the criteria that identifies a site as inappropriate.
This technology is both comprehensive and extremely flexible. Unlike the black-list approach, which excludes sites from users' access, Planetweb technology includes and rates only known sites and does not allow access to sites that have not yet been rated. When a child attempts to enter an Internet site, the site is compared against the constantly updated white list. If the site is on the list and the child is authorized for the site's Planetweb rating, he or she gains access. If the site is not in the white list or the child is not authorized, access is denied.