On November 6, you won’t actually be casting a vote for the candidate of your choice. You will be voting for a group of electors who were nominated by the candidate’s political party in your state; they will vote for the president on December 17.
In most states, plus the District of Columbia, electors are technically required to follow their states’ popular vote; but in others they are not bound by law. So in those states, even if the majority of voters choose Obama, an elector could choose Romney or abstain. This “faithless electing” happened in 2004—but it is extremely rare and has never decided the outcome of an election.
The Electoral College dates back to 1787, when Constitutional Convention delegates decided that the President should be elected by a committee of informed individuals, not by popular vote. In the days before mass media, how could citizens from one state know enough about a candidate from another state to vote for him?
Today there is support for a popular vote; eight states and the District of Columbia have enacted the National Popular Vote bill. But according to the independent, bipartisan U. S. Election Assistance Commission although the system is considered imperfect by some, it will probably remain the process by which we elect the President.