Explained: How is the US President elected

As per the US Constitution — the president must be 35 years of age, be a natural-born citizen, and must have lived in the United States for at least 14 years.

The two main political parties - Republican and Democratic - hold primaries and caucuses across the country during an election year to chose the best candidate to represent them on the ballot. After these primaries, the main contenders are formally selected during their parties' main summer conventions. The incumbent president conventionally remains the key contender of his party and is not challenged.

US citizens actually vote to elect a group of officials (the total being 538) who choose the president and vice-president. The number of electors in a state is proportionate to the size of its population. Every US state gets as many electors as it has lawmakers (Senators and House Representatives) in the US Congress. For example, a densely populated state like California has the highest 55 electors while a sparsely populated state like Alaska has three representatives (the minimum each state gets).

After voters cast their ballot for president, the vote goes to a statewide tally. In 48 states and Washington, D.C., the winner gets all the electoral votes for that state. Two states, Maine and Nebraska, assign their electors using a proportional system.

To win the presidency, a candidate needs an absolute majority vote in the Electoral College, which is half plus one, or 270, the so-called magic number.

In most cases, a projected winner is announced on election night in November after the vote. But the actual Electoral College vote takes place in mid-December when the electors meet in their states.

It is indeed possible and has happened on several occasions in American history-thrice in the 19th century; 2000 between Al Gore and George Bush and 2016 between Hillary Clinton and Donald Trump. Therefore, a presidential candidate is not aiming to win the popular vote across the country but a majority of the Electoral College. Remember, the winner of the popular vote for each state by a plurality will win all of the electoral college votes.

The founding fathers of the US Constitution didn't believe that voters could be trusted to make the correct decision when voting. Hence, they conceived the electoral college as a fail-safe.

If no candidate receives a majority of electoral votes or in case of a tie, the presidential election leaves the Electoral College process and moves to Congress. The House of Representatives elects the President from the 3 presidential candidates who received the most electoral votes. The Senate elects the vice president from the two vice-presidential candidates with the most electoral votes. A candidate must receive at least 51 votes (a majority of Senators) to be elected. If the House of Representatives fails to elect a president by Inauguration Day, the vice-president-elect serves as acting president until the deadlock is resolved in the House.