The Electoral College is the body that elects the president and vice president of the United States. It is established in Article II, Section 1 of the Constitution. It is made up of delegations from each state: each state’s number of electors is equal to its total number of members of Congress.
When citizens in their respective states cast votes for president and vice president of the United States, they are actually casting votes for electors, who are duty-bound to vote for those candidates. However a few “faithless electors” in American history have cast their votes for candidates other than the ones they had pledged to elect. Faithless electors have never changed the outcome of a presidential election.
The Twenty-Third Amendment granted the District of Columbia the number of electors to which it would be entitled if it were a state (but no more than the least populous state.)