One approach missed too many sites, while the other let too many through. To keep up with Internet sites that proliferate at a rate of several thousand each week, filter makers now say they use software with advanced artificial intelligence to mine the Web for text streams. Those that fit certain criteria are automatically added to a list of sites to filter. And they claim teams of editors review the flagged sites to make sure innocent material is not caught in the electronic net. The newer software allows content to be screened page by page to preserve access to a site where some pages are desirable and some aren t.
Customers can decide which content categories sex, violence, drugs, hate or even sports to filter.
Some services can block chat room discussions, e-mail and newsgroups, or let subscribers customize their approved or restricted lists and adjust filtering levels for users of different ages. Filtering software housed on a network server generally is more sophisticated than the versions people load onto home computers. At some institutions, Internet traffic is routed through a network hub or a central server managed by the filter maker or an Internet service provider. Others use an on-site or proxy server at each location. When someone tries to access a site, a short query asks the central computer if the site is appropriate.