As the world remains transfixed on ISIS
, Boko Haram has bombed schools, churches and mosques; kidnapped women and children; and assassinated politicians and religious leaders alike.
What exactly is Boko Haram, and why has it turned into a Nigerian synonym for fear and bloodshed?
What does 'Boko Haram' mean?
The name translates to "Western education is sin" in the local Hausa language.
The militant group says its aim is to impose a stricter enforcement of Sharia law across Africa's most populous nation, which is split between a majority Muslim north and a mostly Christian south.
In recent years, its attacks have intensified in an apparent show of defiance amid the nation's military onslaught. Its ambitions appear to have expanded to the destruction of the Nigerian government.
How long has it been around?
The group was founded 14 years ago by Mohammed Yusuf, a charismatic cleric who called for a pure Islamic state in Nigeria. Police killed him in 2009 in an incident captured on video and posted online.
The crackdown, some say, made Boko Haram more violent and defiant.
took control of the group and escalated the attacks. It murdered and kidnapped Westerners and started a bombing campaign that targets churches, mosques and government buildings.
Why not just kill Abubakar Shekau?
One word: Elusive.
Questions have swirled about Shekau, including whether he's dead or alive. Even his age is unknown -- estimates range between 35 and 44.
In recent years, the Nigerian military has touted his death, only to retract its claim after he appeared alive and vibrant in propaganda videos.
He uses the alias Darul Tawheed, and analysts describe him as a ruthless loner and master of disguise. He does not speak directly with members, opting to communicate through a few select confidants.
Why would Islamist terrorists target the Muslim north?
Despite its religious fanaticism, Boko Haram does not consider all Muslims as supporters and allies.
There have been suggestions that it attacks certain mosques because members have spoken out against it and helped federal officials with their crackdown. Its attacks are aimed at striking fear at the heart of the local population to prevent cooperation with the government, analysts say.
Does the north support the group?
Although the northern populace mostly abhors the violence, there is considerable local sympathy and support for Sharia law, seen by many as the only way to end what is widely regarded as a corrupt and inept government. Poverty is prevalent in the northern region, and as the military struggles to halt Boko Haram's attacks, the militant group is winning perhaps its most important battle: making Nigerians question government competency.
Rights groups have accused local authorities of human rights violations in the fight against the group, adding to the anti-government sentiment.
What's the West doing to help?
The United States has put a $7 million bounty on Shekau's head
. It also designated Boko Haram as a foreign terrorist network. Though it has provided technical and financial support to the Nigerian teams battling the insurgency, there has been a reluctance to put boots on the ground unless there's a direct national security threat to the West. Boko Haram's attacks have been limited primarily to Nigeria and neighboring nations.
Any chance it could attack beyond West Africa?
Whether it does or not, the world should pay attention.
With a population of 175 million, Nigeria is Africa's most populous nation and is considered a political and economic powerhouse in the continent. The key U.S. partner is rich in oil, a major trading partner with China and is the hub of global business in the region.
And as we've learned with Mali, any unresolved local Islamist insurgency has the potential of spiraling into a world problem.
In recent years, Shekau has vowed to attack the United States and Europe.
"Our strength and firepower is bigger than that of Nigeria. Nigeria is no longer a big deal to us, as far as we are concerned. We will now comfortably confront the United States of America," he said in a recent video.
Does it have ties to other terror groups?
The United States says Boko Haram has links to the al Qaeda affiliate in West Africa and to extremist groups in Mali.
But even more unsettling is its recent pledge of allegiance to ISIS,
the Syria-based terror group that has launched attacks across the globe. ISIS ambition is unparalleled, with its sympathizers accused of attacks in the United States.
What other attacks has the group conducted?
The list of attacks is getting longer, and bloodier.
Last year, Boko Haram militants opened fire on northern Nigerian villages, leaving bodies scattered everywhere
and as many as 2,000 people feared dead. Rights groups described it as the terror group's deadliest attack, highlighting its escalating brutality.
Then there's the 2014 attack that sent shock waves worldwide
. Militants stormed a school in the dead of the night, seized nearly 300 schoolgirls and vanished into a dense forest. Their abduction sparked a global movement as throngs took to the streets demanding their rescue. Some remain missing years later.
The terror group has abducted dozens of Christian women, impregnated them and forcibly converted them to Islam or married them off to their kidnappers. It has also used women as suicide bombers.
Its attacks have not been limited to government interests. In 2011, a suicide bomber targeted the United Nations building in Abuja, killing dozens.