(CNN) -- Boko Haram's lethality is indisputable.
The militant group has bombed schools, churches and mosques; kidnapped women and children; and assassinated politicians and religious leaders alike.
It made headlines again recently with the abduction of 230 schoolgirls in the town of Chibok in northeastern Nigeria. After a fierce gunbattle with soldiers, the militants herded the girls out of bed and onto buses, and sped off. Only a few dozen of the girls have escaped.
What exactly is Boko Haram, and why has it turned into a Nigerian synonym for fear and bloodshed?
