The kidnapping of hundreds of Nigerian schoolgirls sparked an international outcry, caused protests in the United States and across the world and drew help from the U.S. as well as other countries.

It has been nearly a month since the abductions. While the basic attention-grabbing fact of the story is easily understandable — hundreds of girls were kidnapped by militants — it’s worth taking a step back to look at what has happened recently, where things stand and, in case you need to catch up, go over the basics of the situation.

Who was kidnapped? How were they abducted?

On April 14, militants kidnapped more than 300 girls from a school in Chibok, located in the remote northeast region of Nigeria. Hundreds of armed militants riding in pickup trucks and on motorcycles arrived, according to a local official, herding girls into the trucks and setting fire to a room in the school before driving into the forest. About 50 girls were able to escape.

Who took them?

Boko Haram, an Islamist extremist group that has killed thousands of people in a series of violent attacks in recent years. (The name means “Western education is sinful.”)

The group was named a Foreign Terrorist Organization by the State Department last November. Its membership ranges “from the hundreds to a few thousand,” the State Department said in its annual terrorism report last year, and the group gets most of its funding from bank robberies and criminal activities like extortion or demanding ransom after kidnappings. (In that sense, it is similar to al-Qaeda and similar groups, which also get most of their funding from similar criminal actions.)

How has the U.S. government reacted?

The White House announced last week that the U.S. was sending a team of military, law enforcement and other personnel to help the Nigerian government search for the missing girls, though White House Press Secretary Jay Carney said that the U.S. was not considering using force or involving troops.

A team of 27 U.S. experts sent to help in the search will contribute U.S. intelligence information and surveillance abilities, the Obama administration said Monday.

Carney said the team includes five State Department officials, 10 Pentagon planners and advisers who were already in Nigeria, and seven more sent from the U.S.-Africa Command, along with four FBI experts in safe recovery, negotiations, and preventing future kidnappings.

“The scope of that assistance has been outlined, and it includes military and law enforcement assistance, advisory assistance, as well as intelligence, surveillance, and reconnaissance support,” Carney said.

All but one of the 27 team members were in place in the Nigerian capital Abuja on Monday, the State Department said.

What kind of surveillance support? Will that include the use of drones?

Although Carney would not provide much detail, his summary was the clearest statement yet that the United States will use its own satellite or other surveillance data and provide intelligence analysis for the search effort, which critics of the Nigerian government contend has been lackadaisical and poorly resourced. Last week, Pentagon officials said that no American surveillance assets had been brought to bear at that point.

A senior Pentagon official said the United States has not mobilized drones to aid the search of the girls. The U.S. military has drones nearby assisting in the search of warlord Joseph Kony, and commanders in African are exploring whether they should be diverted to Nigeria, the official said.

The United States is also likely to provide help monitoring and intercepting communications among members of Boko Haram.

“When we talk about assisting in the effort to locate the girls, we are talking about helping the Nigerian government search an area that is roughly the size of New England,” Carney added. “So, this is no small task. But we are certainly bringing resources to bear in our effort to assist the government.”

Have other governments gotten involved?

In addition to the U.S., France, Britain and Israel have said they will help. Israel said Monday it had forces on the ground in Nigeria, while Britain sent a team with intelligence representatives as well as law enforcement authorities.

Have the girls been seen since they were abducted?

A video believed to be from the Boko Haram group was released on Monday, seemingly showing some of the girls in head scarves and praying. This would appear to be the first glimpse of the abducted girls, coming nearly four weeks after they were first taken.

In this video, which the State Department believes is legitimate, Boko Haram leader Abubakar Shekau says the girls wouldn’t be released until imprisoned Boko Haram militants are freed. This would also appear to be the first indication of what the militants say it would take for them to free the girls.

Mike Omeri, a senior official at the Nigerian Ministry of Information, said at a news conference that the government was “considering all options.”

Asked about new video purporting to show some of the abducted teenagers, Carney said the United States has no reason to question its authenticity. “Our intelligence experts are combing over it, every detail of it, for clues that might help in the ongoing efforts to secure the release of the girls,” he said.

State Department spokeswoman Jen Psaki suggested the United States would oppose anyone paying a ransom for some or all of the girls, but said the Nigerian government is making its own decisions.

“The United States policy … is to deny kidnappers the benefits of their criminal acts, including ransoms or concessions,” Psaki said.

What about that hashtag I kept seeing everywhere?

The #BringBackOurGirls hashtag on Twitter and a parallel campaign on Facebook seemed to help push the story of the missing girls into the mainstream (though it fueled, for the umpteenth time, a debate over whether “hashtag activism” actually accomplishes anything). It often consists of individuals (including public figures like first lady Michelle Obama and British Prime Minister David Cameron) holding up a piece of paper with the hashtag as a way to show their support. The Facebook campaign, in turn, has been promoting rallies held around the globe.

What has the Boko Haram group done in the past?  

In February, Boko Haram attacked multiple villages, setting thousands of buildings on fire and killing more than 200 people, according to the State Department. “We support Nigerian authorities’ efforts to investigate these cowardly acts and to bring the perpetrators to justice,” Secretary of State John Kerry said in a statement at the time. Kerry added that the U.S. would provide counter-terrorism aid to Nigerian authorities to help them combat Boko Haram.

The group was also responsible for “unspeakable violence,” Linda Thomas-Greenfield, the top State Department official for Africa, said in a testimony last year. That violence included attacking the United Nations headquarters in Nigeria’s capital, kidnapping French tourists and shooting more than 100 people in Benisheikh.

Has the U.S. previously helped Nigeria combat this group? 

Former officials and Africa specializes said that Nigeria had not been particularly amenable to offers of assistance from the U.S. “The Nigerians have shown a reluctance to accept not only our assistance but also a reluctance to accept some of our analytic advice,” Johnnie Carson, who was assistant secretary of state for Africa until last year, told The Post last week.

John Campbell, a former U.S. ambassador to Nigeria, said that President Goodluck Jonathan had resisted help. The government had also brushed off American advice about using economic and political outreach to disaffected Muslims in the northern parts of the country.

“The recent ramped-up security assistance to Nigeria is a response to global public outcry which shamed the government in Abuja into accepting help,” J. Peter Pham of the Atlantic Council said. “Up to now, to be fair to the Obama administration, it could only do so much without trampling on Nigerian sensitivities.”

An adviser to Jonathan said last week that terrorism “is very new in Nigeria,” adding that the country was eager to accept help from the U.S.

Was there any warning of the abduction of the schoolgirls?

Amnesty International released a report Friday saying that the Nigerian military had more than four hours of notice about the attack but failed to stop it. The human rights group, attributing this information to sources inside the Nigerian military, said that local groups had “repeatedly alerted” military commands between the evening of April 14 and the early morning hours of April 15. A local government official told the Associated Press that he alerted soldiers guarding Chibok, sending an SOS to barracks an hour’s drive away, but no help arrived.

Ernesto Londoño and Anne Gearan contributed to this report.