The rapid advance of Islamic State fighters across Syria and Iraq this year has been notable not only for its barbarity but for its deft social media operation.
Military advances are routinely accompanied by grim images and videos of the atrocities perpetrated by the extremists. At the same time, Islamic State also takes care to document the donation of toys to children, and televisions and fans to civilians, in the battle for hearts and minds.
Twitter is cracking down on Islamic State accounts but its propagandists are web-savvy.
That is how a 26-year-old Polish student's website has become an essential part of its propaganda machine.
JustPaste.it, owned and managed by Mariusz Zurawek, is being used by Islamic State to upload images of executions, beheadings and massacres.
The free service is run by Zurawek from his bedroom, until recently in his spare time and with occasional help from his brother. The service allows users to upload text, images and video.
It does not require registration, it is not searchable and access to specific content is available only via a link or if it makes the "most popular" page.
JustPaste.it's role in Islamic State propaganda has largely gone unnoticed. All of the images uploaded by Islamic State members have details of a related Twitter account stamped on them, so reporters have been crediting the images to Twitter.
As the United Kingdom intensifies its involvement in Iraq, the Metropolitan police's anti-terrorism unit has paid more attention to JustPaste.it and has asked Zurawek to remove individual Islamic State posts. "I'm in constant cooperation with the UK police, and if they find any illegal materials, they send a take-down notice," he said.
But some posts remain on the site, including a full set of images that document the massacre of up to 500 Yazidi prisoners.
Over the past two months, JustPaste.it has seen a significant increase in traffic from the Middle East. According to Google Analytics, the platform has about 2.5 million unique users a month, about 6 million sessions.