France is choosing a new president in a battle to decide the country's future course, after the Brexit vote in the UK and election of US President Donald Trump.
The race is wide open, with 11 candidates contesting the first round of voting on 23 April. Assuming no candidate wins more than 50% of the vote, the top two contenders will then go through to a run-off on 7 May.
President François Hollande, a Socialist, is not seeking a second term - the first French president to opt out in modern history.
Questions of security are prominent. The first round of voting will come three days after a police officer was shot dead in Paris and five days after two men were detained in Marseille on suspicion of plotting an attack.
What is unusual about this election?
For a start, President Hollande's decision not to run for another term is unprecedented and the candidate chosen to fight for the Socialists, Benoît Hamon, is seen as out of the running.
Not only that, their conservative rivals, the Republicans, have had to battle to stay in the race because their candidate, François Fillon, is at the centre of a judicial inquiry over "fake jobs".
That means for the first time in decades France may be led by a president who does not come from the two big parties of the left or centre-right.
Who could win?
If you believe the opinion polls there are two front-runners, far-right National Front leader Marine Le Pen and centrist Emmanuel Macron.
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Marine Le Pen took over the leadership of the FN from her father in 2011 and has worked hard to "detoxify" the party from its extreme past.Image copyright Getty Images Image caption There are five main candidates: (L-R) Francois Fillon, Benoît Hamon, Marine Le Pen, Emmanuel Macron and Jean-Luc Mélenchon
Mr Macron, a 39-year-old ex-investment banker, was economy minister under President Hollande but resigned in 2016 to fight for the presidency as head of his En Marche! (On the move) party. Not only has he never been an MP - he has never stood for election.
The early favourite was Mr Fillon, but his hopes were dented by allegations that he paid his wife public money for work she did not do. He is now under formal investigation, blaming a political conspiracy, but he is not out of the race and his team is still confident of making the second round.
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A surprise package in the election is far-left stalwart Jean-Luc Mélenchon, whose witty charisma has attracted new supporters.
A 65-year-old former Socialist minister who left the party in 2008, he now leads La France Insoumise (Unbowed France) and has used hologram technology to address separate rallies simultaneously.Image copyright AFP/Getty Images Image caption Eleven candidates are running but only two can go through to the second round
French election 2017: Who are the candidates?
What are the issues?
One of the overriding issues facing French voters is unemployment, which stands at almost 10% and is the eighth highest among the 28 EU member states. One in four under-25s is unemployed.
The French economy has made a slow recovery from the 2008 financial crisis and all the leading candidates say deep changes are needed.
Economic challenges facing next president
The International Monetary Fund estimates that it will be hard to get unemployment down much below 8.5%, and highlights France's "deep-rooted structural rigidities".Image copyright AFP Image caption Dozens of people were killed in the Nice lorry attack on Bastille Day in 2016
In light of the recent attacks, what about security?
It's also high on the agenda.
More than 230 people have died in terror attacks since January 2015 and France remains under a state of emergency. Officials fear more of the hundreds of young French Muslims who have travelled to Syria and Iraq may return to commit new atrocities.
As French voters cast their ballots at 67,000 polling stations across the land, 50,000 police will try to ensure they are safe, and further elite units are on alert.
Many predict attacks linked to Islamists will give a boost to the chances of the right, and particularly Ms Le Pen, who has vowed to suspend all legal immigration and give jobs, welfare, housing and school provision to French nationals before foreigners.
In fact, intelligence services work on the assumption the attackers are deliberately pursuing a Le Pen victory, says the Eyes On Events's Hugh Schofield in Paris - because that could tip the country into chaos.
What's all this about a hologram?
Far-left candidate Jean-Luc Mélenchon kicked off his campaign by appearing at rallies in Lyon and Paris and creating a social media buzz.Image copyright AFP/Getty Image caption Mr Mélenchon's hologram appearance was a masterstroke
He and Ms Le Pen are the masters of social media - she has 1.38 million followers on Twitter, he has 300,000 YouTube subscribers.
The phenomenon of fake news has also made an appearance, with an Algerian news organisation picking up a spoof story that Ms Le Pen planned to build a wall around France and make Algeria pay for it.
- Holograms, mistrust and 'fake news' in France's election
Is the Fillon payment affair fake news?
That's what an investigating judge is hoping to find out.
Satirical weekly Le Canard Enchainé says his wife Penelope was paid €831,400 (£710,000; $900,000) for work as a parliamentary assistant that she did not carry out. One report suggested she did not even have a parliamentary pass or a work email.Image caption Le Canard Enchaine has made a series of allegations about the Fillon family's earnings
She is also said to have pocketed €100,000 for writing just a handful of articles for a literary review owned by a billionaire friend of the family.
Mr Fillon insists everything was above board and says the investigation against him is a "political assassination" designed to deny French voters the choice of a centre-right candidate.
- Fillon payment inquiry: What you need to know
What makes the National Front far-right?
Ms Le Pen is fighting to appeal to the centre and left of French politics after working to move the party away from the image of her father, who has been repeatedly convicted for hate speech and describing the Holocaust as a "detail of history".
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But she still has a far-right platform. She wants to allocate public services to French citizens ahead of foreigners and has vowed to suspend all legal immigration.
The FN also has close ties with other European parties such as Austria's far-right Freedom Party that mainstream right-wing parties want nothing to do with.
- Guide to nationalist parties across Europe