Tracking and blocking websites which feature child pornography brings together domestic users, police forces, internet security professionals and internet service providers (ISPs).
BT owns most of the UK's broadband infrastructure
In the UK, where BT has revealed that its servers block 35,000 attempts to view child pornography each day, domestic internet users are a key link in the chain.
People who discover a site that harbours suspicious content are invited to report the site to the Internet Watch Foundation (IWF).
On its own homepage, the IWF gives pride of place to a large red button bearing the legend "Click here: Report illegal content".
Once a site is reported to the IWF, analysts trained by the National Crime Squad scour the suspicious sites for evidence of illegal content.
Any UK-based site hosting child pornography can be traced quickly and easily, despite elaborate attempts to hide the unique internet addresses, known as IP addresses, which identify each site.
Once traced, the ISP hosting the site is notified and the site taken down.
Unfortunately for those fighting online child pornography, just 20 of 6,000 sites reported in 2005 were based in the UK, the IWF says.
To shut down the rest, the IWF passes on details to the police, who in turn distribute details worldwide via Interpol.
Back in the UK, domestic internet users concerned at the kind of content that might end up on their monitor screens are also protected by the IWF.
The organisation passes on to ISPs its lists of foreign-based sites under investigation for illegal content.
Many of those major domestic internet suppliers then use third-party or in-house filtering technology, such as BT's Cleanfeed, to stop child pornography or abuse reaching screens at home.
However, a continued reliance on user reports of suspicious sights means that the entire system can do little more than react to the proliferation of new sites, rather than reducing the total number of child abuse websites.