The Syrian government and the opposition have agreed to a nationwide ceasefire due to start at midnight, in a breakthrough truce aimed at ending the bloody five-year war.
The deal follows talks between Turkey, Russia, and Iran and could potentially pave the way for a lasting political agreement.
Moscow and Ankara, which support opposing sides in the conflict, promised to act as guarantors.
What does the Syria ceasefire mean?
Russian President Vladimir Putin announced in Moscow that three documents had been signed: an agreement between the Syrian government and the armed opposition on a ceasefire, measures for overseeing the truce and an agreement to start peace talks.
He described the deal as "fragile" but expressed optimism it would hold.
Putin also declared he would reduce Moscow's military contingent in Syria, which has been flying a bombing campaign in support of President Bashar al-Assad since last year.
The decision was likely prompted by Assad's victory in Aleppo, where most of the Russian troops on the ground in Syria had been tied up.
The fall of Syria's second city, dubbed a key strategic prize in the conflict, has handed Putin a victory and the leverage to position Moscow as a Middle East power broker.
What happens now?
Sergei Shoigu, the Russian defence minister, said the truce will include 62,000 opposition fighters across Syria but will exclude Islamic State of Iraq and Levant (Isil) and the formerly al-Qaeda-linked Islamist group Jabhat Fateh al-Sham (JFS).
Leaders from the opposition told the Telegraph all rebel-held areas of Syria would be covered, however the northern city of Idlib was conspicuously not mentioned.
The province of Idlib is largely under the control of JFS and more extreme Islamist groups such as Ahrar al-Sham.
It has become the opposition's largest stronghold and home to thousands of fighters and civilians forcefully evacuated from Aleppo.
The government has escalated its aerial campaign against Idlib since the fall of Aleppo and will likely use the pretext of combating terrorism to continue its strikes on the city in spite of a truce.
Is this the end of the civil war?
Syria has seen several failed ceasefires over the course of the seemingly intractable war,the latest of which in September.
However besides seemed hopeful that the truce would lay the groundwork for political negotiations between the Syrian government and the opposition set to take place next month in Astana, the capital of Kazakhstan.
According to a Russian analyst with close links to the Kremlin, a political deal to end the war, which has claimed as many as half a million lives, could see Assad remain in power until the next presidential election in 2018.
The Syrian opposition and its allies had previously made the removal of the Syrian president a precondition for talks. However, Turkey appears to have softened on the demand after repairing ties with Russia, Assad's chief international ally.
Assad could then be replaced by a less polarising candidate from his Alawite sect, said Andrey Kortunov, director general of the Russian International Affairs Council think tank.
"A couple of names in the leadership have been mentioned (as potential successors)," said Kortunov, declining to name anyone.
Will Syria be partitioned?
Syria could effectively be carved up by major powers to create something resembling a federalist state: Turkey and the opposition in control of the so-called buffer zone along the Syrian border and the government in control of the country's major cities including Aleppo.
Syrian Kurds may well be allowed their own semi-autonomous territory in the northeast, much like Kurdistan in Iraq.
Such cooperation between Russia and Turkey would have been unthinkable until recently.
The two had entered a diplomatic crisis when the Turkish air force shot down a Russian jet in November 2015, but a deal over the summer to repair relations saw them cooperating on Syria for the first time.
What about the Americans?
The deal, which was reached without the US, also underscores the West's diminishing role.
Washington had been the rebels' chief broker, but talks with Moscow had become deadlocked and little progress was made during some nine months of talks.
- Originally published in Telegraph UK