Barack Obama has been elected as the first black president of the United States.
In a victory speech in his home city of Chicago, the 47-year-old promised change and a new dawn of leadership.
Mr Obama spoke after sweeping a series of key battleground states in a landslide electoral college victory.
He pledged to be a president of all Americans and vowed to overcome challenges which were "the greatest of our lifetime", including two wars, a global economic crisis and a planet in peril.
"I promise you, we as a people will get there," he said.
Cheered on by tens of thousands of supporters, Mr Obama took to a stage lined with US flags with his wife Michelle and young daughters Malia, 10, and Sasha, seven, at his side.
Delivering his message of hope and unity, Mr Obama told those whose support he had not won: "I hear your voices, I need your help and I will be your president too."
He said he would listen to his opponents, adopt a multilateral approach to world affairs and told those watching outside the US that "our stories are singular but our destiny is shared.
"The new dawn of America leadership is at hand," he said.
"To those who would tear the world down, we will defeat you.
"To those who seek peace and security, we support you.
"And to all those who have wondered if American's beacon still burns as bright, tonight we've proved once more that the true strength of our nation comes not from the might of our arms or the scale of our wealth, but from the enduring power of our ideals: democracy, liberty, opportunity and unyielding hope.
"That's the true genius of America."
He went on: "The road ahead will be long, our climb will be steep. We may not get there in one year, or even in one term, but America I have never been more hopeful than I am tonight that we will get there.
"I promise you, we, as a people, will get there."
