Barack Obama has won a second term as US president, defeating his Republican rival Mitt Romney in a closely contested battle that seemed almost too close to call till the end.
Obama, who four years ago was elected as the US' first African American president, won 303 electoral votes.
As celebrations broke out across the country, a victorious Obama tweeted: "Four more years."
"We're all in this together. That's how we campaigned, and that's who we are. Thank you," said another tweet from Obama, the son of a Kenyan father and a white American mother.