Hosni Mubarak has stepped down as president of Egypt, after weeks of protest in Cairo and other cities
The news was greeted with a huge outburst of joy and celebration by thousands in Cairo's Tahrir Square - the heart of the demonstrations.
Mr Mubarak ruled for 30 years, suppressing dissent and protest, and jailing opponents.
US President Barack Obama said that Egypt must now move to civilian and democratic rule.
This was not the end but the beginning and there were difficult days ahead, he added, but he was confident the people could find the answers.
"The people of Egypt have spoken, their voices have been heard," he said. "Egypt will never be the same again."
"They have made it clear that nothing less than genuine democracy will carry the day."
'God help everybody'Announcing Mr Mubarak's resignation, Vice-President Omar Suleiman said the president had handed power to the army.
Mr Suleiman said on state TV that the high command of the armed forces had taken over.
"In the name of God the merciful, the compassionate, citizens, during these very difficult circumstances Egypt is going through, President Hosni Mubarak has decided to step down from the office of president of the republic and has charged the high council of the armed forces to administer the affairs of the country," he said.
"May God help everybody."