Child abuse image content list
The child abuse image content list (CAIC List) is a list of URLs and image hashes provided by the Internet Watch Foundation to its partners to enable the blocking of child pornography & criminally obscene adult content in the UK and by major international technology companies. Launched by BT as Cleanfeed in July 2004, as of 2009 the list covered 98.6% of UK internet connections.
Source: Wikipedia — Child abuse image content list (CC BY-SA 4.0)