From the future of U.S.-Iranian relations to the fate of another missing American, Sunday's release could mark just the beginning of more political maneuvering to come.
Iran detained Rezaian in 2014, eventually charging him with espionage and other crimes, according to The Washington Post. He was the newspaper's Tehran bureau chief.
Hekmati was detained in 2011, weeks after arriving in Iran to visit his grandmother, according to his family's website
. The former Marine infantryman and Arabic and Persian linguist was accused of espionage and other charges in 2012.
Abedini, an Iran native and convert to Christianity, was arrested in 2012 and convicted the next year on charges of attempting to undermine the Iranian government. He had been sentenced to eight years in prison.
Not much is known about Khosravi-Roodsari.
Who else was released?
Matthew Trevithick, a student who was recently detained, was also released -- but not as part of the prisoner swap. He arrived Sunday night in Boston, according to his stepmother, Susan Trevithick.
U.S. officials indicated to Iran's foreign minister "that it'd be important for them to try to resolve some of the other cases of Americans detained in the context of this" deal, a senior administration official told CNN.
Where are they?
Rezaian, Hekmati and Abedini arrived Sunday at Ramstein Air Base in Germany, and they were scheduled to undergo medical checkups at Landstuhl Regional Medical Center, a U.S. military hospital.
Hekmati's family released a photo Monday showing him with two sisters and a brother-in-law along with U.S. Rep. Dan Kildee, D-Michigan. They spent about 15 minutes together, according to a brief statement from the family.
The Washington Post released a photo of Rezaian
, showing him and family members smiling broadly.
The Americans' flight from Iran was delayed for a time due to confusion over the whereabouts of Rezaian's wife and mother, whom U.S. officials had insisted be part of the release deal. On Monday, U.S. Secretary of State John Kerry said in an interview with CNN's "New Day" that Iran's foreign minister and other officials understood the terms of the agreement included the two and ensured it happened.
"All's well that ends well," he said.
Khosravi-Roodsari decided not to leave Iran, senior White House officials said. "It's his free determination" whether he wants to stay in Iran, one official said. "We don't make that judgment."
What happens next?
It's unclear how long the medical evaluations would take, but the former prisoners met with friends and family Monday.
The American Center for Law and Justice
, a Washington-based group dedicated to protecting religious and constitutional freedoms, reported that Abedini was tortured during his imprisonment and beaten by fellow prisoners in June. He suffered injuries to his face at the time, the center reported.
Hekmati suffered from health problems, including weight loss and breathing difficulties, according to his family.
Jared Huffman, who represents Rezaian and has been involved in his case, said the journalist, Hekmati and Abedini won't be on U.S. soil for a few days.
Jason Rezaian's brother, Ali Rezaian, told CNN on Monday that his sibling is "in good spirts" and excited about getting out and seeing people, but first has to "focus on getting better."
What did Iran get in return?
In exchange for the American prisoners' freedom, Washington pardoned or commuted the sentences of an Iranian and six dual citizens of the United States and Iran in what President Barack Obama called a "one-time gesture."
The men allegedly had been involved in exporting products and services to Iran in violation of trade sanctions against the country. They were accused of exporting goods ranging from electronic components and satellite services to marine navigation and military equipment to Iran.
Khosrow Afghahi, Tooraj Faridi, Bahram Mechanic and Nima Golestaneh were pardoned. Nader Modanlo, Arash Ghahreman and Ali Saboonchi had their sentences commuted, the U.S. Justice Department said.
The United States also agreed to drop charges against 14 other Iranians whose extradition seemed unlikely, a U.S. official said.
On Monday, Iranian Foreign Ministry spokesman Hossein Jaberi Ansari said that 28 Iranians "were freed or were relieved of judicial restrictions" under the agreement.
He did not name them.
Did the nuclear deal play a role?
The announcement of the prisoners' release came as the U.N. nuclear watchdog, the International Atomic Energy Agency, announced Sunday that Iran is in compliance with a July deal to restrict its nuclear program.
As a result, at least some international economic sanctions against Iran were lifted.
The prisoner swap came after more than a year of secret negotiations, officials said.
Kerry has said the nuclear agreement "accelerated" the prisoner exchange, but he told CNN on Monday that talks on the nuclear deal were on a "separate track" from the swap.
Is Iran holding any other Americans?
During negotiations, another American's name was apparently on the table: Robert Levinson
Iran has denied holding Levinson, a former FBI agent and CIA contractor who went missing there in 2007.
Now the agreement between the United States and Iran calls for Iranian officials to "continue cooperating with the United States to determine the whereabouts of Robert Levinson," a U.S. official said.
Kerry said Sunday that Iran had agreed to deepen coordination in the search.
"We are happy for the other families," Levinson's family said in a statement. "But once again, Bob Levinson has been left behind. We are devastated."