A senior Muslim Brotherhood leader, Essam al-Arian, said that Egyptians had made history and were adding a new model of democracy to the world. The leader of the opposition al-Ghad party, Ayman Nour, spoke of the nation being born again.

The protests began on the 25 January,

partly

inspired by the demonstrations that drove the Tunisian President Zine El Abidine Ben Ali from power, partly driven by Egypt's economic problems and anger against what many saw as a corrupt regime. John Simpson looks at what made President Mubarak leave now.

For 18 days, the

stubbornness

of one elderly man has been

pitted against

the will of millions here. The Egyptian army found itself in the middle, unwilling until the very end to force President Mubarak out, yet deeply

hostile

to any suggestion that the soldiers should remove the demonstrators from Tahrir Square by force.

It's still too soon to know for certain what made Mr Mubarak step down, but it seems a reasonable

assumption

that the army leadership could see the hairline cracks appearing among their own officer corps.

The generals were

inclined to

side with the president, one of their own, and the more junior officers sympathised with the demonstrators.

World News from the BBC

President Barack Obama has welcomed President Mubarak's resignation. He called on the military to lift the state of emergency and start preparing the way for free and fair elections. He said he was optimistic about Egypt's political future.