Who are Boko Haram ... and what do they want

Boko Haram is Nigeria’s biggest Islamist group. Founded by Mohammed Yusuf in Maiduguri in 2002, Boko Haram was initially a non-violent group. But since Yusuf’s death in police custody in 2009, it has grown increasingly violent under the stewardship of new leader Abubakar Shekau, culminating in the massacre earlier this month of 2,000 people in the town of Baga.