Katy Watson
South America correspondent in São Paulo

The polling centres were busy here in São Paulo, the places we visited all had lines of people queuing up to cast their vote.

Some were wearing the Brazilian football shirt, the colours an indication of their support for Bolsonaro. Others were dressed in red, or wearing stickers saying "Out with Bolsonaro" – their support for Lula clear.

As the afternoon went on, those dressed in red started walking up to Avenida Paulista, São Paulo’s most famous street. It’s here that Lula will make an appearance if he wins with enough points to avoid a run-off.

His supporters are already gathering here to celebrate what they expect to be win. They will be cheering regardless of whether it's only the first round or an outright victory.

Laura Trevelyan
BBC World News presenter in Rio de Janeiro

As counting is under way in Brazil’s election, Mauricio Santoro, professor of international relations at Rio State University, tells me lines to vote are so long that in some places polling stations are being kept open so everyone gets a chance to vote.

He reminds us that only once in recent presidential election history has a candidate won in the first round - Fernando Henrique Cardoso - in 1994 and 1998.

Voting has been brisk here, with long lines as voters queue up to have their say after a polarising campaign. Some were reluctant to advertise who they were voting for, with several telling the BBC they were avoiding wearing the colours of either candidate.

This stems from fears that this could be an election with a contested result, as Bolsonaro has made unfounded claims that the outcome may be rigged against him.

Vanessa Buschschlüter
Latin America digital editor in Rio de Janeiro

Possibly, but not necessarily.

This is the first round of the election. A candidate needs more than 50% of the valid votes to win outright.

If no candidate reaches that threshold, there will be a run-off between the top two candidates in four weeks, on Sunday 30 October.

Whoever gets more votes in that second round will then be declared president-elect.

The new president will be sworn in on 1 January 2023.

Image source, Reuters

Luiz Inácio 'Lula' da Silva

• 76 years old
• left-wing
• former metal worker
• was president from 2003-2010
• imprisoned in 2018 on corruption charges but his conviction was later thrown out

Image source, Getty Images

Jair Bolsonaro

• 67 years old
• far-right
• former army captain
• running for a second consecutive term as president
• has cast unsubstantiated doubts on the trustworthiness of Brazil's electronic voting system

Image source, Getty Images

It's now 17:00 local time (20:00 GMT) in Brazil’s capital, Brasilia, and voting stations have closed.

Unlike the last presidential elections, voting has come to a close at the same time across Brazil’s four different time zones.

This means voting stations in Acre, Brazil’s north-west, are closing at 15:00 local time.

And given voting in the country is done electronically, we're expecting a result to be declared fairly shortly.

In the next few moments, polls will come to a close across Brazil as the country takes part in the first round of its presidential election.

The two main candidates, President Jair Bolsonaro and former President Luiz Inácio 'Lula' da Silva, have already voted in Rio de Janeiro and São Paul respectively.

Image source, EPA

Image source, EPA

Image source, Reuters

Image source, EPA

Image source, Getty Images

Vanessa Buschschlüter
Latin America digital editor in Rio de Janeiro

Image source, Getty Images

Many voters have turned up at polling stations in Rio wearing either red - the colour of Lula’s Workers’ Party flag - or the country’s yellow football shirt, which has become closely associated with the Bolsonaro camp.

But with some voters wary after a tense election campaign, there are those who are opting for subtlety.

Sonia, 87, who was wearing a blue shirt, lowered her voice when she pointed to her friend Eva, 83, who was wearing green: “If you put our two outfits together, they make up the colours of the Brazilian flag, and that’s a sign we back Bolsonaro.”

“I am a patriot, and I don’t want our country to become like Venezuela,” she whispered, referring to the fear many Bolsonaro supporters share that a left-wing government could drag Brazil into an economic crisis like the one crippling its northern neighbour.

Juliana Gragnani & Jake Horton
Disinformation team & Reality Check

Image source, Getty Images

Voting in Brazil is done electronically, as has been the case since 1996.

Each candidate has a number, and on election day voters type the number of their chosen candidate into a voting machine at polling stations across the country.

The votes are then counted by the machines, and the totals are sent electronically to a central office.

Votes from across the country are tallied up and a final result is announced, usually within hours of polls closing.

Each machine also prints out a paper copy of the totals for each candidate.

When polls close, the totals are displayed publicly at polling sites, and each machine's votes can be compared with the total recorded by the electoral court.

This year, for the first time, these paper copies will be published online on the day of the vote.

You can read more here.

Katy Watson
South America correspondent in São Paulo

This has been billed as the most important vote since Brazil returned to democracy in the 1980s – and that’s because more than 30 years on, there have never been so many doubts about the future of the country's democracy.

Bolsonaro came to power as an anti-establishment figure. He’s long questioned the reliability of the voting system. He's alleged fraud without evidence and it’s a narrative willingly adopted by many supporters who’ve said they won’t accept a win by frontrunner Lula.

Another big beef of Bolsonaro’s is the role of the Supreme Court. Its power has grown since he has been in power – supporters of that argue it's an effort to counteract the president undermining the rule of law. Critics maintain the court has gone beyond its remit.

Lula’s critics, meanwhile, say the former president is corrupt and a return to power would be a step back for the country’s democracy. But Brazil has a history of dictatorship, and Bolsonaro has been clear in his support of that dark era of history.

The fear among many is that another four years of Bolsonaro will lead to a darker future too.

Vanessa Buschschlüter
Latin America digital editor in Rio de Janeiro

This is the first round of the presidential election. The main two candidates are President Jair Bolsonaro and his arch rival Luiz Inácio Lula da Silva, best known as Lula.

There are also nine other candidates in the running for the presidency, but opinion polls suggest they are trailing far behind.

A candidate must win more than 50% of the valid votes cast in order to be declared president outright.

If none of the candidates gets the necessary votes, a run-off will be held between the top two on 30 October.

More than 130m Brazilians are registered to vote and voting is obligatory for citizens between 18 and 70 years of age.

Over the next few hours, our colleagues in Brazil, London, Washington and Miami will be bringing you developments as they happen and explaining the ins and outs of this hugely significant presidential vote.

It’s a battle between opposite political poles as left-wing ex-President Luiz Inácio Lula da Silva is trying to unseat the current far-right President Jair Bolsonaro.

And the stakes are high, with the country of 215 million people facing an economic crisis and high inflation.

Stay with us.