Washington: Barack Obama is the third consecutive president of the US to retain office after his predecessors George W Bush and Bill Clinton.
Obama became the only African American to hold the office of President in 2009 and he has now defeated Republican Mitt Romney to get a second term in the White House.
His predecessor George W Bush served as US president from 2001 to 2009.
William J Clinton, better known as Bill Clinton, became president in 1993 and went on to retain his office till 2001.
Before him, George HW Bush had a single term from 1989-93.
His predecessor Ronald Reagan won in 1981 and then retained the presidentship, with his term ending in 1989.
Three presidents before him - James Carter 1977-81, Gerald R Ford 1974-77 and Richard M Nixon 1969-74 - served single terms.
The norm is that no US President serves more than two terms.