Hundreds have gathered in London to celebrate the Egypt uprising and show solidarity with people still living under repressive regimes.
People waved banners and listened to speeches at the Amnesty-organised rally in Trafalgar Square.
Foreign Secretary William Hague said it was important for the UK to help Egypt build "political parties and civil society over the coming months".
Egypt President Hosni Mubarak resigned on Friday after 18 days of protests.
The country is now in the hands of the high command of the armed forces, headed by the defence minister.
The BBC's Gabriel Gatehouse said Trafalgar Square sounded and looked a bit like Tahrir Square, the focal point of the demonstrations in Egypt, with Middle Eastern music and banners proclaiming "victory to the Egyptian revolution".
He said it had been organised before Mr Mubarak stood down and the event had turned into a celebration.
"This means everything," said Cairo-born Sarah Abdel Gawad, draped in an Egyptian flag. The 28-year-old teacher said although Egypt's future might not be easy, it was paramount the people were allowed free and fair elections.
"And then if there are mistakes along the way, at least they are the mistakes of the people," she said.
Iranian Azadeh Assadi, 34, said it was essential Egyptians did not take their new freedom for granted.
"This means another dictator is gone. I am so happy for Egypt," she said. "But I hope they don't take it for granted. The same thing happened in Iran 30 years ago."
Salil Shetty, Amnesty's secretary general, told the crowd: "We are here to show solidarity with the people of Egypt who have achieved the impossible in a couple of weeks.
"We want to send a resounding message from Trafalgar Square to Tahrir Square that we are in solidarity with the people of Egypt."
'Battle of wills'
Sarah el-Rashidi, from the New Egypt Organisation which was set up during the protests, said: "We need to celebrate firstly but straight after this weekend we can start to establish a roadmap for the future."
Vivian Ibrahim, who had been organising protests outside the Egyptian embassy in London during the uprising, told the BBC that Egyptians were happy the army had stepped in.
"What we want to see now is a transition to a civilian government," she said. "We want to hear the voices of the youth, who stood in Tahrir Square. We want their considerations taken into account."
Sharif Mansour, an Egyptian pro-democracy activist based in London who was involved in helping the protesters in Egypt get their message across, had four bits of advice for people in other countries who desire a similar revolution.
"Lose their sense of fear because it's a battle of wills, not violence. Distil their points to the most accurate - there are many voices and groups but it has to be one point that is put across," he said.
"Show the world they just want their rights as any person would and instil a sense of national pride for everyone."
Mr Hague said people should not be afraid of change but of "upheaval and instability" in the Middle East following the resignation of Mr Mubarak, who had been guarantor of the peace treaty with Israel.
He told BBC Radio 4 Today's programme that the ousting of the Egyptian president should "jolt" Israelis and Palestinians to get back around the negotiating table to find a Middle East peace settlement.
"Perhaps one of the good things that might come from events in Egypt and Tunisia is that policymakers in Israel and among Palestinians will be jolted to see that it is vital now to take this forward because in a few years time a two-state solution will be much, much more difficult to achieve," he said.
The rally in Trafalgar Square finished at 1400 GMT but many Egyptian supporters remained in the square to continue the celebrations.
Amnesty International has organised rallies in 16 countries to express "solidarity and defiance" with people living under what the humanitarian organisation calls repressive regimes across North Africa and the Middle East.