- Why now?
The election comes after last month's presidential election in which Emmanuel Macron beat Marine Le Pen in the second round.
Elections to France's National Assembly follow presidential elections so that the new president can form a government.
If his or her party wins a majority of seats, a government that supports his or her programme can be formed.
If not, his or her party can try to form a coalition with other parties.
If that fails the president will be forced into what the French call a "cohabitation" with a government of a different political persuasion.
The upper house, the Senate, is elected by an electoral college at a different time, this year on 24 September.
Who can stand?
With a few exceptions for soldiers and some state officials, any French citizen can stand, as long as they are of voting age, of sound mind, registered to vote and have set up a campaign account.
Most, but not all, candidates stand for political parties, ranging from the far left to the far right and from large mainstream groupings to tiny locally based groups, and they can be endorsed by more than one party.
Why are there two rounds?
All French elections have two rounds of voting, an arrangement that encourages a certain political pluralism.
The first round serves to eliminate those with the least support.
If one candidate wins more than 50 percent in the first round, no second round is necessary.
If not, the two with the highest votes automatically go through to the decider, as do any candidates with the backing of more than 12.5 percent of registered voters, meaning that the final round can be a two-way, three-way or even four-way showdown.
The candidate with the highest vote in the second round is the winner, even if that vote is not over 50 percent.
How many candidates are there in 2017?
A total of 7,882 candidates are standing for 577 seats, 11 of them representing French citizens living abroad.
Their average age is 48.5 years.
More than 42 percent of them are women, meaning that the next parliament may well surpass the 26.9 percent female representation in the outgoing one, which was itself a record.
More than 200 MPs hav chosen not to stand again, one reason why the new parliament is likely to be very different to its predecessor.
How many people will vote?
A total of 46,978 million people are registered to vote, a rise of 1.8 percent on the previous electoral register.
Some 716,000 of them are 18-years-old and thus first-time voters this year.
But not all of them will cast their ballots.
The abstention rate has been rising over the years, from 22.8 percent in the first round in 1958 to 42.78 percent in the 2012 first round.
The highest turnout since 1958 was 84.9 percent in 1978's second round, the lowest was 55.41 percent in the 2012 second round, the last parliamentary election.
When will we know the results?
Polls open at 8.00am and close at 8.00pm in the large towns.
First estimates will be available as from then but final results may not be available until many hours after polls close.
You can follow the results live via the graphics on RFI's website.