The US elections take place on Tuesday, 2 November 2004, when tens of millions of voters will cast their ballots in the climax of the presidential campaigns.
How does the presidential election work?
The president is not elected directly by the people, but by an Electoral College. Each state sends a certain number of electors to the college, based on the size of its population. In almost every state, the winner of the popular vote gets all the Electoral College votes in that state.
In rare instances, a candidate can win in the Electoral College without winning the popular vote.
There was confusion over the final election result in 2000
This is what happened in 2000 - for the first time in more than a century. George W Bush won the large state of Florida by a tiny margin and therefore got all its electoral votes, winning him the presidency even though fewer people voted for him nationwide than chose Democrat Al Gore.
There are 538 votes in the Electoral College. The number per state equals the number of its representatives in Congress plus the number of senators. This gives small states a slight advantage because all states have the same number of senators - two - regardless of size.
For example, California has 55 electoral votes - about 10% - though it has 12% of the US population. Wyoming has three electoral votes representing 0.56%, though it has only 0.18% of the US population.
Will we know the result on Election Day?
If the race is very close - as all the polls suggest it will be - there could be a repeat of the kind of post-election court battles that delayed the result in 2000.
Both the Republicans and the Democrats have marshalled thousands of election observers to watch for irregularities - and lawyers to fight them in court if need be.
Problems in Florida in 2000 have led to new voting methods being introduced
Legal challenges could focus on anything from voter eligibility to the machinery of the election itself. Some counties still use the punch cards that left chads hanging four years ago; others use electronic machines which may or may not leave a paper record of how citizens voted.
Both sides have been in court right up to Election Day trying to win any possible advantage they can via the legal system.
Why does the popular vote not determine the presidency?
When the US Constitution was written in 1787, the 13 original states fiercely guarded their rights, with small states fearing they would be overwhelmed by larger ones.
At the time, there was also little enthusiasm for entrusting the election of the president directly to the people. So the task was given to an Electoral College and each state legislature was given the right to choose its delegates.
Over time, political parties asserted their right to choose these delegates, and today they are elected.
If no candidate wins a majority in the Electoral College, the House of Representatives chooses the president.
How are the candidates chosen?
John Kerry was chosen as the Democrat candidate after he won the most support in almost all the state caucus gatherings and primary elections.
The preliminary contests picked delegates to the Democratic Party's national convention held in Boston in July. There, Mr Kerry was formally nominated as the party's presidential candidate and he accepted the nomination.
George W Bush has campaigned on security issues
George W Bush became the official candidate of the Republican Party at its national convention in New York City. While a rival could have emerged during the primary season at the beginning of the year, Mr Bush did not face a challenge.
What is the timetable?
The day of the election is 2 November, though many states allow people to vote early in designated places or through postal ballots.
It will mark the end of a long campaign which has covered the primary season, the conventions and the three televised presidential debates held in late September and October.
The winner is scheduled to be inaugurated president on 20 January 2005. In the intervening period, the current administration carries on.
What are the main issues?
Mr Bush is making the "war on terror", which he declared after 11 September 2001, the centrepiece of his campaign, claiming that he has made America safer.
Mr Kerry challenges that and also accuses Mr Bush of mishandling the war in Iraq.
But while security is top of the agenda in this, the first presidential election since 11 September 2001, both sides are also highlighting their plans on domestic issues.
John Kerry has challenged the president over the war in Iraq
Mr Kerry regularly points out that Mr Bush is set to be the first president since the 1930s Great Depression to lose jobs on his watch, while Mr Bush says the economy is recovering and charges that his opponent will raise taxes.
Both sides raised large sums of money, which has enabled them to keep campaigning in the battleground states right up to election day.
What about third-party candidates?
Ralph Nader, the veteran consumer activist, is standing again. He announced his intention in February.
He stood in 2000 for the Green Party but did not win its nomination this time. Supporters of Al Gore argued that if Mr Nader had not been in the race, their man would have won.
The Nader response was to say that he was campaigning against both major establishment parties on major issues of importance which needed discussion and that his supporters might not have voted at all otherwise.
The Green Party is fielding its own candidates again, putting David Cobb forward for president.
And the Libertarian Party's Michael Badnarik is standing for president and is on the ballot in 48 out of the 50 states plus the District of Columbia.
Is this just an election to choose the president?
The main election is for the presidency, which is contested every four years.
But there are also elections for one-third of the 100 senators (actually 34 seats this year) the whole of the House of Representatives (435 seats) and many state governors, as there are every two years.
Bush's party hopes to maintain control of Congress
US senators serve for six years and the device of having only one-third up for election each time is one of the checks and balances built into the American system. The representatives serve for only two years so they face elections very often.
A president may serve two terms only. President Bush, first elected in 2000, is trying for his second term.
He also hopes his Republican Party will retain control of the House and Senate, which together make up Congress.
They hold the 100-strong Senate with 51 seats. Democrats have 48 seats and there is one independent. The Republicans hope to consolidate this majority, perhaps by winning Democrat-held seats in Florida, Georgia and South Carolina. But it might well be a close fight for as many as 10 seats.
Republicans also command the House of Representatives with 227 out of the 435 seats. Democrats have 205 and there is one independent. Again, Republicans hope and expect to hold onto the House.