The Nigerian Islamist extremist group Boko Haram, which claimed the kidnap of a French family of seven whose release was announced on Friday, has led a years-long insurgency in Nigeria. Here are some key facts on the group:
CURRENT STATE: Boko Haram has grown from a northeastern-focused sect targeting local leaders and police to a many-headed monster capable of deploying suicide bombers to attack the United Nations, police headquarters and one of the country's most prominent newspapers.
TOLL: Its insurgency and the armed response are believed to have left some 3,000 people dead since 2009, including killings by the security forces. In a report in October 2012, Human Rights Watch said Boko Haram was believed responsible for at least 1,500 of 2,800 deaths since 2009, with security forces also accused of major abuses.
ORIGINS: An early version of the group formed in 2004. Boko Haram means "Western education is sin" in the Hausa language spoken in Nigeria's north. It is believed to have a number of factions with differing aims, including some with political links and a hard-core Islamist cell.
AIMS: Initially claimed to be fighting for the creation of an Islamic state in the north, but a range of demands by different people have since been issued, including the release of its members from prison.
CRIME: Criminal gangs are also believed to have carried out violence under the guise of Boko Haram. Conspiracy theories abound as well, including whether enemies of President Goodluck Jonathan, a southern Christian who faces strong opposition in the north, have backed the violence.
LEADERSHIP: Its first real leader was the late Mohammed Yusuf, who convinced young people to join him despite having only elementary knowledge of the Koran, according to one professor who has studied the sect. His former deputy Abubakar Shekau is widely believed to currently lead Boko Haram's main Islamist cell, which says it wants to be known by a different name, roughly translated as "People Committed to the Prophet's Teachings for Propagation and Jihad".
UPRISING: Boko Haram launched an uprising in 2009, leading to nearly a week of fighting that ended with a military assault which left some 800 dead and the group's mosque and headquarters in northeastern Maiduguri in ruins. Yusuf was captured and later killed when police said he was trying to escape.
RE-EMERGENCE: Boko Haram went dormant for more than a year before reemerging in 2010 with a series of assassinations. Bomb blasts, including suicide attacks, have since become frequent and increasingly deadly.
KIDNAPPINGS: Boko Haram had never before claimed a kidnapping prior to the abduction of the French family, suggesting it has again shifted tactics in its campaign. A Boko Haram splinter faction, known as Ansaru, has however been blamed for a number of kidnappings of foreigners.
AFFILIATES: Diplomats say Boko Haram members have sought training from Al-Qaeda's north African branch in northern Mali. Western nations closely monitor the group for signs of more extensive cooperation.
AMNESTY: Calls have grown for Nigeria's government to offer an amnesty deal to the Islamists to end the violence. Nigerian President Goodluck Jonathan this week formed a committee to look at how such a deal would be offered.