Nigeria's Boko Haram group explained - in 60 seconds
6 May 2014 Last updated at 09:06 BST
Nigeria's militant Islamist group Boko Haram is fighting to overthrow the government and create an Islamic state.
The group has caused havoc in Africa's most populous country through a campaign of bombings and attacks.
In a video obtained by the AFP news agency, Boko Haram leader Abubakar Shekau said the group was responsible for the abduction of more than 200 schoolgirls from the northern state of Borno on 14 April, saying that it planned to sell them.
BBC News outlines the background, leadership and methods of the group - in 60 seconds.
Video produced by Jasmine Coleman