One of the largest collections of online material belonging to the group calling itself Islamic State has been discovered by researchers at the Institute of Strategic Dialogue.
The digital library contains more than 90,000 items and has an estimated 10,000 unique visitors a month. Experts say it provides a way to continually replenish extremist content on the net.
But taking it down is difficult because the data is not stored in one place. And despite counterterrorism authorities in Britain and the U.S. having been alerted to this growing repository, it continues to grow.