The US presidential election takes place on 5 November. But it's possible the candidate with the most votes won't be the winner.

This is because the president is not chosen directly by the voters, but by what's known as the electoral college.

Here's how it works.

When Americans take part in November's presidential election, most of them will cast a vote for either Democrat Kamala Harris or Republican Donald Trump.

But that vote actually goes towards shaping the make-up of a group of officials who will represent Ms Harris or Mr Trump in the electoral college.

The word "college" here simply refers to a group of people with a shared task. These people are electors and their job is to choose the president and vice-president.

The electoral college meets every four years, a few weeks after election day, to carry out that task.

The number of electors from each state is roughly in line with the size of its population. Each state gets as many electors as it has lawmakers in the US Congress (the House and Senate).

California has the most electors - 54 - while a handful of sparsely populated states like Wyoming, Alaska and North Dakota (and Washington DC) have the minimum of three.

There are 538 electors in total.

Each elector represents one electoral vote and a candidate needs to gain a majority of the votes - 270 or more - to win the presidency.

Generally, states award all their electoral college votes to whoever won the poll of ordinary voters in the state.

For example, if a candidate wins 50.1% of the vote in Texas, they are awarded all of the state's 40 electoral votes. Alternatively, a candidate could win by a landslide and still pick up the same number of electoral votes.

It's therefore possible for a candidate to become president by winning a number of tight races in certain states, despite having fewer votes across the country.

Advantages:

• smaller states remain important to candidates
• candidates don't need to travel the whole country
• recounts are easier because officials can isolate the issue in one state

Disadvantages:

• lots of voters feel their vote does not matter
• too much power resides in swing states (see below)
• the popular vote winner can lose the election (more on that later)
• risk of fake electors (more follows on that too)

Most states consistently vote for the same party each election.

This is why presidential candidates target specific "swing states" where the vote could go either way rather than trying to win over voters across the country.

In 2024, the top battleground states are Arizona, Georgia, Michigan, Nevada, Pennsylvania and Wisconsin.

Yes. In fact, two out of the last six elections were won by candidates who had fewer votes from the general public.

In 2016, Donald Trump was almost three million votes behind Hillary Clinton. In 2000, George W Bush defeated Democratic candidate Al Gore who won the popular vote by more than half a million.

Only three other presidents have been elected without winning the popular vote, all of them in the 19th Century.

When the US constitution was being drawn up in 1787, a national popular vote to elect a president was practically impossible (country size and tricky communications).

So, the framers of the constitution created the electoral college, with each state choosing electors.

Smaller states favoured the system as it gave them more of a voice than a nationwide popular vote to decide the president.

The electoral college was also favoured by southern states where slaves made up a large portion of the population. Even though slaves didn't vote, they were counted in the US Census (as three-fifths of a person).

Since the number of electoral votes was determined by the size of a state's population, southern states had more influence in electing a president than a direct public vote would have given them.

In some states, electors could vote for whichever candidate they prefer, regardless of who voters backed. But in practice, electors almost always vote for the candidate who wins the most votes in their state.

If an elector votes against their state's presidential pick, they are termed "faithless". In 2016, seven electoral college votes were cast this way, but no result has been changed by faithless electors.

In some states, "faithless" electors can be liable for fines or prosecuted for their votes or abstaining.

In 2020, US voters became familiar with the concept of "fake electors" after pro-Trump Republicans in seven US states created their own electors in a bid to overturn the election's results.

In some cases, they created and signed official-looking documents or arrived at state capitals on 14 December - when electors across the country met to officially cast their votes.

Some of those involved have faced prosecution and investigations are still ongoing.

If there is no majority winner, the House of Representatives, the lower house of US lawmakers, will then vote to elect the president.

This has happened only once, when in 1824 four candidates split the electoral vote, denying any one of them a majority.

With two parties dominating the US system, this is unlikely to happen today.