Boko Haram's attack in Baga, Borno State, which killed hundreds, possibly thousands, on 3 January has once again drawn attention to the Islamist militant group that has been terrorising northern Nigeria for more than five years.

The group is responsible for the deaths of approximately 9,000 people in total, according to the Council on Foreign Relations' Nigeria Security Tracker, though estimates vary and this number does not include January's attack. The Nigerian government has said there were 150 deaths in the Baga attack, but other reports suggest it was as many as 2,000. Amnesty International has said it could be the group's deadliest attack to date.

Boko Haram's international profile rose dramatically after the abduction of more than 250 schoolgirls from Chibok village, Borno state in April 2014, leading to the worldwide #BringBackOurGirls campaign. But these girls, most of whom are yet to be found, are just a fraction of the number of people Boko Haram has captured in the past couple of years. 40 young men were reportedly taken from Malari village in the northeast on 31 December 2014.

WHAT IS BOKO HARAM?

The name 'Boko Haram' roughly translates as "western education is sinful", although its full name, which is rarely used (Jama'atu Ahlis-Sunnah Lidda'awati Wal Jihad) is Arabic for the "Sunni Community for the propagation of the Prophet's Teachings and Jihad".

Islamism, roughly defined, is a political form of Islam, though there are many different strands, including both militant and peaceful forms. It is often fused with a strongly anti-Western position, rejecting the perceived immorality of the West. While many Muslims would want to see some influence of Sharia in governance, Islamists seek to entirely replace secular governance with Sharia law.

Boko Haram claims to seek to establish an Islamic state, overthrowing western involvement in government and society, particularly education. The majority of those killed have been Muslims and young men, though its anti-western ideology also makes it strongly opposed to Christianity. And while religious ideology is one motivation, it is not the only one; there are sectarian divisions, inequality and corruption which create an environment for such groups to thrive.

WHO ARE THEY?

It has become more prominent since 2009, when the current leader Abubakbar Shekau came to power. Before then it operated as a less violent religious movement, which was less concerned with overthrowing the government.

Originally formed in 2002 under the Islamist cleric Mohammed Yusuf, then group was based at a headquarters in Madiguri, the capital of Borno State. It had approximately 10,000 followers in north-eastern Nigeria, as well as neighbouring Cameroon and Niger, many of whom were clerics and students.

Amid growing sectarian tensions, an uprising in July 2009 saw an outbreak of fighting between Boko Haram and Nigerian security forces. Yusuf was killed by the national forces, along with a number of members of the group, in what has been described by Human Rights Watch as an extra-judicial execution. His body was left on public display and shown on Nigerian state television in a display of strength over the group.

But it wasn't long before it became clear that the threat had not passed, only become more violent. According to international affairs think tank Chatham House, the movement fragmented into smaller groups, and radical violent elements suppressed the more moderate, peaceful members of the original sect. One particularly notable splinter group emerged in 2011, known as Ansaru. It has since become a terrorist group in its own right, distinguishing itself from Boko Haram by attacking international targets, and may have formed connections to Al-Qaeda in the Islamic Maghreb.

The now more militant Boko Haram group is led by a man who claims to be Abubakbar Shekau, though there have been numerous rumours that he is dead.

GROWING STRENGTH

Since Shekau came to power the group's attacks have moved beyond Borno into neighbouring Yobe and Gombe states and occasional attacks in the south of the country. There have been numerous suicide bombings as well as attacks on churches – something that had not previously been done.

In August 2011, the group attacked the United Nations building in the Nigerian capital, Abuja, killing 23 people. In 2012, Boko Haram assisted another militant group who had abducted French hostages, although these attacks on foreign citizens do not appear to be core to the group's purpose.

In January 2012 Shekau gave Christians in northern Nigeria an ultimatum to convert to Islam or to leave, in keeping with the group's aims to establish an Islamic state.

It was listed as a terrorist organisation by the United States in 2013. In May the same year the Nigerian government declared a state of emergency in Borno state, which has since been extended to Yobe and Adamawa states.

According to Chatham House, the terror organisation moved into a new phase in 2014, which demonstrated a growth in confidence. The think tank estimates that there are now between 6-8,000 members, up from 4,000 in 2009, with 15,000 Nigerian army soldiers based in Borno state trying to combat them.

But despite the presence of Nigerian forces, in August 2014 Shekau declared a caliphate in the region it controls in Yobe and Borno states, an area of about 20,000 square miles, according to the Telegraph. There are suggestions that Boko Haram has been influenced by Islamic State in Iraq and Syria, who declared a caliphate in that region in June 2014, driving hundreds of thousands from their homes in northern Iraq.

2015 ELECTIONS

There are fears that religious tensions will intensify in the run-up to the election in February and possible violence after the vote, the International Crisis Group reports. The two major parties are the ruling People's Democratic Party (PDP), led by Christian President Goodluck Jonathan, and the All Progressives Congress (APC), whose key figures are all from the majority-Muslim north, although political parties have been warned not to politicise religious differences. Another concern is that the state of emergency in three north-eastern states could prevent people in that region from being able to vote, which would make the vote unrepresentative and possibly unconstitutional.

The President has faced significant criticism for his failure to suppress Boko Haram, and the Nigerian government is suspected of underestimating the numbers killed in attacks to downplay the threat. But January's attack on Baga has thrown the militant group back into the international media spotlight, and Jonathan will face pressure at home and abroad to prevent it from further gaining in strength.

The current focus is on short-term security in order to allow the elections to happen as peacefully as possible, but the new president will need to look to long-term options, such as how to improve the military response in the northeast, as well as looking to structural changes that could foster peace and prevent interminable conflict.