The Burmese military authorities have released the pro-democracy leader, Aung San Suu Kyi, from house arrest.
Appearing outside her home in Rangoon, Ms Suu Kyi told thousands of jubilant supporters they had to "work in unison" to achieve their goals.
The Nobel Peace Prize winner has been detained for 15 of the past 21 years. It is not yet clear if any conditions have been placed on her release.
US President Barack Obama welcomed her release as "long overdue".
UN Secretary General Ban Ki-moon said Ms Suu Kyi was an "inspiration", and called on Burma to free all its remaining political prisoners.
Ms Suu Kyi, 65, was freed after her latest period of house arrest expired and was not renewed by the military government.
Her release comes six days after the political party supported by the military won the country's first election in 20 years. The ballot was widely condemned as a sham.
For more than 24 hours crowds of people had been waiting anxiously near Ms Suu Kyi's home and the headquarters of her now-disbanded National League for Democracy (NLD) party for news of her fate.
Many wore T-shirts sporting the slogan "We stand with Aung San Suu Kyi".
On Saturday afternoon, a stand-off developed between armed riot police and several hundred people gathered on the other side of the security barricade blocking the road leading to her lakeside home. Some of them later sat down in the road in an act of defiance.
As tensions rose, reports came in at about 1700 (1030 GMT) that official cars had been seen entering Ms Suu Kyi's compound, and then that unnamed officials had formally read the release order to her.
Hundreds of people then surged forward and rushed forwards to greet her.
The ecstatic crowd swelled to three or four thousand before Ms Suu Kyi, in a traditional lilac dress, finally appeared, about 30 minutes later, on a platform behind the gate of her compound.
She took a flower from someone in the crowd and placed it in her hair.
Ms Suu Kyi then tried to speak, but was drowned out by the noise of the crowd, many singing the national anthem and chanting her name repeatedly.
"I have to give you the first political lesson since my release. We haven't seen each other for so long, so we have many things to talk about. If you have any words for me, please come to the [NLD] headquarters tomorrow and we can talk then and I'll use a loud speaker," she joked.
"There is a time to be quiet and a time to talk," she added. "People must work in unison. Only then can we achieve our goal."
She then went back inside her home for the first meeting with NLD leaders in seven years. She also spoke to her youngest son, Kim Aris, who was awaiting her release in neighbouring Thailand. Ms Suu Kyi had two sons with late husband, British scholar Michael Aris.
International leaders were quick to welcome Ms Suu Kyi's release.
Mr Ban said she was an "inspiration", but he regretted that she had been excluded from the elections.
He said he hoped no further restrictions would be placed on Ms Suu Kyi, and urged the Burmese authorities "to build on today's action by releasing all remaining political prisoners".
The head of the Association of Southeast Asian Nations (Asean), Surin Pitsuswan, said he was "very, very relieved" and hoped the move would "contribute to true national reconciliation".
President Obama called Ms Suu Kyi "a hero of mine".
"Whether Aung San Suu Kyi is living in the prison of her house, or the prison of her country, does not change the fact that she, and the political opposition she represents, has been systematically silenced, incarcerated, and deprived of any opportunity to engage in political processes," he said.
UK Prime Minister David Cameron also said the release was "long overdue", describing her detention had been a "travesty".
"Aung San Suu Kyi is an inspiration for all of us who believe in freedom of speech, democracy and human rights," he added.
The ruling junta has restricted Ms Suu Kyi's travel and freedom to associate during previous brief spells of liberty, and has demanded she quit politics.
However, earlier this week her lawyer said that she would "not accept a limited release".
A BBC correspondent in Rangoon says it is unlikely the ruling generals would have freed Ms Suu Kyi unless they felt confident she no longer represented a threat to them or their plans for the country.
Sunday's elections were a key step in a carefully planned transition from overt military rule to a nominally civilian government, but the process has been widely condemned as widely fraudulent and un-democratic, she adds.
State media have reported that the biggest military-backed party, the Union Solidarity and Development Party (USDP), has secured a majority in both houses of parliament. Those elected included the leader of the USDP, Prime Minister Thein Sein, who retired from the military as a general in April to stand.
A quarter of seats in the two new chambers of parliament will be reserved for the military. Any constitutional change will require a majority of more than 75% - meaning the military will retain a casting vote.
The NLD - which won the last election in 1990 but was never allowed to take power - refused to contest the election, which means that legally it is no longer a political entity. By extension Burma's most famous democracy campaigner now has no official political status and an unclear role.
Our correspondent says the next few days might provide some answers on how Ms Suu Kyi plans to further the cause of freedom of justice in Burma, for which she has sacrificed so much to achieve, but in the meantime thousands of her supporters are just enjoying the moment.