Hamas took more than 200 hostages from Israel. Here’s what we know.

How many hostages does Hamas have?

Over 240 hostages were taken by Hamas and other attackers on Oct. 7. There are 121 hostages abducted that day remaining in Gaza, most of them Israeli, including dual nationals, according to Israel.

Israel’s count of remaining hostages includes those whom Israel has concluded are no longer alive. Israel says officially that 37 of the remaining hostages abducted on Oct. 7 are dead, but Israeli and American officials estimate privately that the number of dead hostages could be much higher . The Israeli military reported in May the recovery of the bodies of seven hostages, all of whom it said were killed on Oct. 7.

Separately, Israel said Hamas is holding the bodies of two Israeli soldiers killed in the 2014 Gaza war. Two other Israelis were captured by Hamas before Oct. 7, bringing the total number of known Israeli hostages, dead or alive, to 125, according to Israel’s count.

Hamas, a group that the U.S. designates as a terrorist organization, said in April that it didn’t know if it could deliver 40 living civilian captives to satisfy a U.S.-backed cease-fire proposal, according to officials familiar with the negotiations. The number of hostages who are alive and dead has been central to cease-fire proposals, which feature the exchange of hostages for Palestinian prisoners held by Israel.

“The state wants to know if it is working to bring back bodies or [living] hostages," said Ofer Merin , who is director general at Shaare Zedek Medical Center in Jerusalem and a member of the committee that determines hostage deaths.

In the months since the Hamas attack, Israel has adjusted its estimate of the number of remaining hostages as some were freed, investigators identified victims of the attacks and the Israeli military recovered bodies from Gaza.

Hamas isn’t holding all of the hostages who remain in Gaza. Palestinian Islamic Jihad, a Hamas ally that the U.S. has designated a terrorist organization, said in October that it was holding more than 30 people abducted on Oct. 7. Hamas transferred some of its own hostages to other factions, according to Israel, complicating efforts to secure their freedom.

Israeli officials said on Dec. 3 that at least three civilian women and two children were being held by militants outside Hamas, citing their latest intelligence. That group included Israeli-Argentinian citizen Shiri Bibas and her two sons, Ariel, 4, and Kfir, 10 months, who were kidnapped by Hamas and later handed over to another faction.

Hamas has said that Bibas and her sons were dead, but Israel hasn’t confirmed that. A hostage reported by Palestinian Islamic Jihad to have died in captivity, Hanna Katzir , was released under the Israel-Hamas cease-fire deal.

When will the hostages be released?

Talks on the release of hostages and a temporary cease-fire have repeatedly stalled. Families of captives have banded together to keep hostage recovery at the top of Israel’s agenda.

Hamas had released 109 hostages as of the end of November when a cease-fire agreement that included hostage-prisoner exchanges expired. Of those, 105 were returned during the pause in fighting that began on Nov. 24, including 81 Israeli or Israeli dual nationals, 23 citizens of Thailand and one from the Philippines.

The exchanges involved only women and minors. Hamas regards Israeli men of fighting age as soldiers and a more valuable commodity.

In October, Hamas released four civilians, and the Israeli military reported the recovery of a soldier during ground operations in Gaza.

What was the Israel-Hamas hostage deal?

Israel and Hamas began a temporary cease-fire agreement on Nov. 24 under which civilian hostages abducted by Hamas were released in exchange for Palestinian prisoners in Israel . The agreement ended when Israel said Hamas was unable to produce a new list of hostages, prompting Israel to resume its military campaign. Talks to resume the exchanges have since stalled.

Hamas released additional hostages during the cease-fire under separate agreements with other countries.

Under the cease-fire pact, Israel also agreed to allow the delivery of fuel to Gaza from Egypt and to pause drone surveillance in northern Gaza for six hours a day.

During the first phase of the cease-fire, Hamas released 50 civilian hostages in exchange for 150 Palestinian prisoners over a period of four days, in addition to hostages released under separate agreements. Israel and Hamas extended the agreement for a total of three days, continuing a pattern of three Palestinian prisoners to be exchanged for each Israeli hostage. The releases under the deal involved only women and minors on both sides, though Hamas released men from Thailand and a Russian hostage under separate agreements.

Prime Minister Benjamin Netanyahu said the recovery of hostages remains one of Israel’s war goals along with the elimination of Hamas.

What does Hamas want in exchange for hostages?

Hamas has demanded an Israeli cease-fire, the release of Palestinian prisoners held in Israeli jails and, in recent negotiations, the free movement of displaced Palestinians to northern Gaza. Israel has rejected the unconditional return of Palestinians to the north. An estimated 1 million Palestinians have been pushed to the south of the Gaza Strip by the war.

Prisoner exchanges have figured prominently in the long-running Israel-Palestinian conflict. In 2011, militants in Gaza released the Israeli soldier Gilad Shalit after more than five years in captivity, in a swap for 1,027 Palestinians—including a senior Hamas leader , Yahya Sinwar , who is a primary target of Israel’s military campaign in Gaza.

Who are the hostages?

The people taken captive in Gaza come from 29 nations including Israel, with women, children and the elderly among them. Many hold dual nationalities. They include dozens of workers from Asia or Africa, many of them Thai farmers.

Some of the hostages were attending a music festival in southern Israel near the Gaza Strip; some were residents or visitors at kibbutzim, the farming communities in the area, where many people were slaughtered in terrorist attacks.

The captives remaining in Gaza include 17 women and two of the 39 children abducted on Oct. 7, according to Israel. Some of the remaining women are members of the Israeli military. Foreign citizens still held captive include eight from Thailand, two of whom were determined in mid-May to have died.

The White House said in mid-December that eight Americans, including three male soldiers, remained hostage . Three have since been declared dead, their bodies held by Hamas, including husband and wife Gad Haggai , 73 years old, and Judi Weinstein , 70, and Itay Chen , a 19-year-old Israeli sergeant. Haggai and Weinstein were killed on the day of the attack , according to a spokesman from their kibbutz . Chen was also killed by Hamas on Oct. 7, President Biden said in a statement marking his death .

Who were the two hostages rescued in Rafah?

The Israeli military rescued two hostages , Fernando Simon Marman and Louis Har, in a raid in the southern Gaza city of Rafah on Feb. 12. The two men had been abducted from Kibbutz Nir Yitzhak, near the Gaza border, on Oct. 7. In the rescue operation , military forces and a police SWAT team broke into a house in Rafah and engaged in a gunfight with Hamas militants while shielding the hostages before evacuating them, the Israel Defense Forces said.

Where are the hostages in Gaza being held?

Early in the war, Hamas said the hostages were kept in locations across Gaza to impede Israeli military operations in the crowded Palestinian enclave. The remaining hostages are believed to be held in sections of Hamas’s extensive tunnel network that the Israeli military has yet to clear. In a tunnel raid in the city of Khan Younis, in southern Gaza, the Israeli military said it found evidence that about 20 hostages had been there. The two hostages rescued on Feb. 12 were being held in Rafah.

Tamar Metzger, 78 years old, who was released after 53 days, was held in tunnels in Khan Younis. She described to The Wall Street Journal enduring her time in captivity in an underground room with a group of other hostages, under the watch of four captors. Yocheved Lifshitz , one of four hostages released in October, also described being held underground in what she described as a spiderweb of deep, wet underground tunnels.

What signs of life have emerged from Gaza?

Hamas released a video on April 24 of American-Israeli hostage Hersh Goldberg-Polin , in which the 23-year-old said he was nearing his 200th day in captivity, suggesting it had been filmed shortly beforehand. Goldberg-Polin’s fate had been uncertain after witnesses and video from Oct. 7 indicated that Hamas attackers had blown off his left arm. Appearing with the stump of one arm, he pressed for Netanyahu to strike a deal with the group to free the remaining captives.

Noa Argamani , a 26-year-old university student whose abduction to Gaza on the back of a motorbike was seen in a widely shared video, appeared in a video released by Hamas on Jan. 15. A released hostage said that she had been held with Argamani for four days in an apartment under Hamas’s watch.

Eitan Gonen , father of Romi Gonen , 23, who was kidnapped from the Nova music festival, was told by released hostages that his daughter was wounded but alive.

How has Hamas treated the hostages?

The hostages released by Hamas endured grueling conditions that health experts said would have lasting psychological, if not physical, effects— especially for the children .

Their captors provided inadequate food and water and refused to provide medication, according to accounts from family, friends and doctors who treated some of those who were released.

A hostage released in November described older captives spending days lying on mattresses and said their captors took away glasses and hearing aids when they were abducted, making it difficult for some to see or hear. Hostages were held in small groups, moved around Gaza and separated from loved ones, sometimes just before being released. Some have been forced to make propaganda videos.

The released hostages struggled to adjust to light and suffered from a lack of vitamin C and physical exercise after being held in cramped conditions underground for weeks, according to a doctor. Some were treated for injuries sustained during their abduction or captivity. Most were in stable or good condition, doctors said, though an 84-year-old woman was released in critical condition .

Most of the child hostages released in November had lost between 10% and 15% of their body weight, doctors said. Many had rashes from being held in unsanitary conditions and wounds that had become infected.

Many of the children spoke in whispers after their release and ate little, saying they had to save food for later, a doctor said, a reflection of the conditions under which they were held. Some had trouble sleeping, a sign of drug withdrawal after their captors drugged them to keep them quiet and induce sleep, a psychiatrist said.

This explanatory article may be periodically updated.

Write to Peter Saidel at Peter.Saidel@WSJ.com and Summer Said at summer.said@wsj.com