The spiral of violence 
When 130 people were killed by Islamist militants on the streets of Paris, the outpouring of sympathy and support was resounding
Russia in Syria: What will happen next?
Frank Gardner on five likely consequences of Russia's campaign in Syria
Lucrative business
Inside the Islamic State kidnap machine
Watch/Listen
BBC reporter on frontline against IS
Calling in air strikes against IS
How IS is spreading terror worldwide
The priest who escaped IS captivity 
Face-to-face with IS militantsBackground
Who's in charge of IS?
Who's in charge of IS?How Islamic State functions - in 90 seconds
Features and Analysis
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Who runs IS?
How Islamic State makes its 'Caliphate' work
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IS, war and money
Conflicts in Syria and Iraq make for dirty business
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Women within IS
BBC Security correspondent Frank Gardner reports on Islamic State's dual attitude towards women and their value to the movement.
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'The new caliph'
The shadowy power behind Islamic State
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Killing machine
Can IS militants' savagery be explained?
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Inside Mosul
Escapees explain how militants overran their city
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Russia moves
What is Putin's end game in Syria?
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Peace with militants?
Should anyone ever talk to IS?