Park Geun-hye can be detained for up to 20 days during investigations into allegations of corruption and abuse of presidential power that led to her impeachment.
What are the allegations against her?
Park has been accused of abuse of political power and corruption along with her long term confidant Choi Soon-sil.
During the impeachment trial, prosecutors accused Park, and Choi, of bullying 16 business groups, including Samsung, into making "donations." Fearing retaliatory measures and tax investigations, Samsung was forced to donate $69 million for the launch of two ventures that Choi managed, prosecutors said.
She is also accused of scheming with top bureaucrats, denying financial assistance to officials critical of her policies.
Park is also alleged to have passed classified information to Choi.
She was jailed on Thursday because prosecutors said the accusations against her are "grave."
Is she being held in a prison?
Shortly, after the court issued a warrant against Park, she was taken to the Seoul Detention Centre in the outskirts of Seoul.
The centre is known for the high profile figures previously lodged there – an army-backed ex-president jailed in the 1990s for bribery, a former spy chief, and SK Group chairman Chey Tae-won.
At the Seoul Detention Centre in Uiwang, she will join other key figures in the scandal, including Choi Soon-sil and Samsung icon Lee Jae-yong.
What will her days in prison be like?
For starters, she will have to readjust from living in a sprawling presidential palace to a tiny prison cell.
Park will be held in solitary confinement where she is expected to rise at 6:30am and go to bed by 9:00pm.
Given her status, the only privilege she may have over other inmates will be slightly more space, a toilet and shower in an adjoining room.
She will also be provided with a foldable mattress on the floor, a television, a small cupboard, a toilet, and a cold-water sink.
No outside food is allowed. She will be provided three meals a day budgeted at $1.30 each, and will be required to wash her tray at the sink before taking it back.
She is likely to have been served a simple lunch of rice with bean sprouts, kimchi, cabbage stew, and seaweed on her first day, Friday, the standard fare according to officials.
Getting her hair styled professionally will be another privilege that Park will have to give up. She has never been seen without a perfect chignon. Even after 14 hours of interrogation by prosecutors last week, she was seen with the style intact.
"Getting your hair permed or done by someone from outside the facility is against equality among inmates," Kim Kyung-soo, a retired prosecutor told Reuters.
"It will be difficult for [Park's side] to insist they need an outsider to come in and do her hair," Kim said.
A hairdresser is available but services are limited to cutting hair. Cosmetics are limited to toners and lotions. Hair colouring is also unavailable.
Detained inmates are given unlimited meeting time with their lawyers but visitors are restricted to one per day.
So who will takeover as the new leader?
Among the first of the many big, uneasy questions is what happens next?
As of now, the only answer is more politics.
South Korea must elect its next leader in little under two months and more than half a dozen candidates are in contention.
The front runner is Moon Jae-in, a veteran lawmaker who lost to Park in 2012, and is now leading in early polls. Viewed as less confrontational toward North Korea and China, he is credited with initiating dialogue to halt the North's nuclear and missile threats.
Zhang Baohui, professor of political science and director of the Centre for Asia Pacific Studies at Lingnan University in Hong Kong, is optimistic about South Korea's ability to withstand this political crisis.
"This will not lead to massive chaos in South Korea," he said. "I am not expecting huge political turbulence in South Korea.