You've been hearing a lot tonight about the leaders of the Liberal and Conservative parties - Trudeau and O'Toole. While one of them is most likely to be prime minister, there are other politicians who could play key roles if no party wins a majority.

Jagmeet Singh, 42, is leader of the progressive New Democratic Party (NDP). The social media-savvy Singh is by far the most popular leader in the country, boasting a 42% approval rate, according to polls by Abacus Data. But unfortunately for Singh, his likeability hasn’t always translated into a high seat count. Heading into election day, his NDP were polling at around 20%, roughly 10 points behind the leaders.

Maxime Bernier, 58, leads the right-wing People’s Party of Canada. The 58-year-old formed the party in 2018 after quitting the Conservative party amid backlash over statements he made about immigration and multiculturalism. His party favours limited immigration, an end to corporate welfare and rejects what it calls “climate change alarmism”. Once considered a fringe party, the PPC has picked up some support this time around, now polling at around 6%.

Yves-François Blanchet, 56, runs the separatist Bloc Québécois. This party only runs candidates in Quebec, where it typically competes against the Liberals for most seats in the province.

Annamie Paul, 48, is the new leader of Canada’s Green Party. She is the first Black Canadian and first Jewish woman to serve as leader of a Canadian federal party. It’s been a bumpy road for the political rookie. She lost one of her three MPs who left in protest after Paul’s comments on the Israel-Palestine conflict and later faced internal challenges to her leadership.

Jessica Murphy
BBC News, Montreal, Québec

Canadian election outcomes can be tough to predict.

This time, there are two frontrunners, that's clear - Justin Trudeau's Liberal and Erin O'Toole's Conservatives.

Most poll analysis suggests the most likely scenario is another minority government - but a lot of factors can shift the eventual seat count for each party.

First of all, under Canada's system of government, a federal election is really 338 separate races, with candidates from various political parties running in each of the country's federal ridings (constituencies).

Looking at national polling numbers also don't give a full picture of voting intentions across Canada. Sometimes, one party could have a strong showing in places with a lot of seats up for grabs like Quebec and Ontario, giving them the advantage.

With multiple parties in the running, vote splitting can also come into play in some ridings.

One example would be a riding where two progressive parties are competitive. If progressive voters are split between the two parties, sometimes a third party can "come up the middle" and win.

That's why in the final days of the campaign, both O'Toole and Trudeau urged supporters who might be flirting with smaller political parties to rally behind their respective banners.

And a lot comes down to each party's get out the vote efforts and how motivated their supporters are to make it to the polls on election day.

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Should you stay up late tonight to see who wins? Or can you go to bed early because we won't know a winner until Tuesday?

Well, we just don't know yet.

The majority of votes will be counted in the coming hours - but 1.2 million Canadians requested mail-in ballots, and Elections Canada says counting of those won't begin until Tuesday.

So if the election is close - in key swings seats, and in the national battle to win the most seats in parliament - those mail-in votes could be decisive.

This is what we do know:

• There are 32 seats in Atlantic Canada up for grabs
• Liberals are leading in 24, Conservatives 8 and the NDP 2, though it's early and votes are still being tallied
• There are a total of 338 seats in parliament up for grabs
• Polls close in Ontario, Quebec, at 21:30EST (03:30GMT)
• The final votes will be cast in British Columbia at 22:00EST (04:00GMT)

So we could get a sense of who's won within a few hours of the polls closing - or the count could end up taking days.

Ramanuj is a lawyer who immigrated to Canada eight years ago. He voted Liberal in 2019 but has since had a change of heart over who best aligns with his values.

Who are you voting for and why?

I voted for the Conservatives this time. Fundamentally, they seem a bit more fiscally responsible and O’Toole seems a bit more centrist on a personal level as opposed to an extreme right-winger.

Socially, I am liberal and progressive. On an economic level, I am conservative, so my values seem closer to the Conservatives this time. Last time, I was a bit more closely aligned with the Liberal Party.

What is your "ballot box" issue and why?

The economy. It has an effect on everybody and everything: housing, the cost of goods and services, salaries, the Covid recovery.

The economy is struggling, so the government is looking for sources of revenue and increasing taxes. People are struggling to get up the housing ladder and to come back from the pandemic. The money has to come from somewhere.

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Voters in Canada’s Francophone province have been known to deliver a surprise on election night.

In 2019, the success of the separatist Bloc Quebecois was a major factor in denying Justin Trudeau’s Liberals a majority government. Trudeau will have to aim for a stronger showing this time if he hopes to pick up seats.

He’ll face stiff competition from the Bloc, but will also see challenges from Jagmeet Singh’s New Democratic Party and Erin O’Toole’s Conservatives.

O’Toole has made a major push to improve his party’s seat count in the province. In 2019, Conservatives won just 10 of the province’s 78.

“O’Toole has been more compromising to Quebec than any leader of the party since Brian Mulroney,” said Richard Johnson, a professor emeritus of political science at the University of British Columbia.

In 1984, Mulroney led the Progressive Conservatives to the largest majority in Canadian history, partially due to his support in Quebec.

Holly Honderich
BBC News, Oshawa, Ontario

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The ring of suburbs around Toronto - dubbed the 905 because of its telephone area code - are must-win ridings (constituencies) for any candidate hoping to form government.

“The 905 plus belt around is going to be where this election is won and lost,” Queen’s University politics professor Elizabeth Goodyear-Grant told the BBC. “And with a few exceptions, this region tends to vote as a bloc.”

Increasingly diverse, these small towns are predominantly made up of middle-class Canadians and families with young children. The 905 is home to more people than the capital city of Ottawa, with more swing seats per capita than almost anywhere else in the country.

Look for ridings like Richmond Hill, Whitby and Markham-Stouffville. All three have their Liberal incumbents deadlocked with their Conservative competitors.

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Each of Canada’s federal parties has areas of support in British Columbia (BC).

The lower mainland, which generally comprises the regional districts of Metro Vancouver and the Fraser Valley - is typically considered Conservative territory.

In the last two decades, the Conservatives have won the area's 13 seats 70% of the time.

A notable exception was in 2015, when the Liberals won big, helping them on to a majority.

So keep an eye on BC. How the Liberals and Conservatives do here may give a hint about which party will form government.

Results are coming in slowly from the eastern provinces of Canada - but it's too soon to tell which party has a real lead.

The action really begins an hour from now, at 21:30 EST (03:30 GMT), when polls close across Ontario and Quebec.

Anthony Zurcher
BBC North America reporter

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For four years, Justin Trudeau was viewed by many on the American left as a shining liberal counterpoint to Donald Trump’s conservatism.

He was everything the brash US president wasn’t – young, idealistic and a champion for international co-operation and progressive values on the environment, healthcare, race and culture.

When Americans grew despondent about their domestic situation, they had Trudeau’s spats with Trump and a wealth of panda memes to give them comfort.

For the most part, the US tends to tune out Canadian politics. But if Trudeau were to lose tonight, Americans would take notice.

Many would view it as a warning sign to Biden and US Democrats that the political right is once again on the rise around the world - even in Canada. And while Canadian conservatism is a far cry from Trump’s populist movement, and Trudeau has had stumbles and controversies that are unique to Canadian politics, American Republicans would certainly see it as a harbinger of better days ahead. Even a diminished Trudeau would be considered an encouraging development.

A Trudeau victory, on the other hand, would ensure that Biden continues to have a North American partner for his international efforts and an ideologically kindred spirit to work with on the sometimes delicate US-Canadian relations on trade, the environment and immigration.

Regardless of partisan affiliation, Americans may wistfully look at the vote tabulations in Canada on Monday evening and recall what it’s like to have a smoothly run national election free from delays, chaos and seemingly unending accusations of fraud.

Robin Levinson King
BBC News, Toronto, Ontario

There are many close races expected tonight, but unlike events south of the border, Canadians are not expecting the results of the entire election to be contested.

Canada is known for its polite and relatively cordial elections, compared to the United States. That is largely because all elections are governed by Elections Canada, whereas in the US each state oversees voting separately.

Political scientist Matthew Lebo lived in the US for 20 years, before returning home to Canada to teach. He says he was "surprised by how brazen efforts are to make it harder for some people to vote", in the US.

Here's why it's easier to be a voter in Canada than the US.

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The pandemic hasn't just impacted lines at the polling station, it's also been a main talking point on the campaign trail.

Cases of the fast-spreading Delta variant have been surging in Canada - and how the government has handled Covid-19 has become an important electoral issue.

Trudeau is in favor of vaccine mandates, while O’Toole has said he favors testing instead.

O’Toole has been on the defensive since Alberta’s conservative premier, Jason Kenney, publicly apologised for relaxing Covid-19 restrictions too early and mishandling the public health crisis.

Trudeau has used his handling of the pandemic as a way to criticise the Conservative Party and woo voters.

"We do not need a Conservative government that won’t be able to show the leadership on vaccinations and on science that we need to end this," Trudeau told reporters last week.

To date, 1.57 million coronavirus cases have been recorded in Canada, as well as more than 27,300 deaths. The country has one of the world’s highest vaccination rates, with nearly 85% of the population having had at least one dose.

Jessica Murphy
BBC News, Montreal, Québec

Pandemic safety measures meant some voters have had to queue to cast their ballots today.

Elections Canada, which administers federal elections, had warned that a combination of staffing shortages, social distancing measures, and a reduced number of polling stations in some areas could cause longer wait times - and they sure did.

Some voters posted pictures on Twitter of the lines, which are unusual for Canada.

Holly Honderich
BBC News, Oshawa, Ontario

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Before we get any further in our coverage, we need to introduce Erin O'Toole.

If you’re unsure who he is, you're feeling like a lot of Canadians did just a short time ago.

At the start of the campaign in August, according to Abacus Data, 40% of Canadians didn't know enough about Mr O'Toole to even form an opinion about him.

But the new Conservative leader has exceeded expectations, putting his party within striking distance of Trudeau’s Liberals.

O’Toole, 48, has led a softer, more moderate campaign than some of his predecessors, trying to compete with Trudeau for Canada’s progressives.

Read more about the man who could unseat Trudeau:

Erin O'Toole: The man that could take down Trudeau

Holly Honderich
BBC News, Oshawa, Ontario

So far so quiet at the Conservative's election night party in Oshawa, Ontario.

Conservative party staff and members of the media are milling about inside a mostly empty arena while crews finish set up.

One man is carefully steaming the large Canadian flags flanking the stage.

Life is a Highway by Tom Cochrane blasts on the speaker - before being cut out by a temporary power outage.

Still, it might prove to be an upbeat night here, after a better than expected campaign performance by Conservative leader O'Toole. Latest polls put O'Toole just half a point behind Trudeau's Liberals.

If you're just tuning into Canadian politics or stumbled upon this page by chance, there's one term you need to know: a riding.

A riding is a geographical electoral district, known as a constituency in the UK. In the US, it would be a voting district.

Each riding contains one elected member of Canada's House of Commons.

In this election, individual races are being held in 338 ridings across Canada.

Whichever party wins the most ridings determines the next prime minister, with a few caveats - which we'll get into later.

Polls have just closed in the eastern province of Newfoundland and Labrador.

Seven ridings are at stake.

The Conservatives, Liberals, New Democratic Party and the People's Party of Canada are all on the ballot. There are no Green Party candidates running in the province.

Justine is a teacher and - upset with housing prices and costs in Vancouver - she will not be backing Justin Trudeau’s Liberals in this election.

Who are you voting for and why?

I'm going to be voting for Jagmeet Singh and the New Democratic Party (NDP). I have voted Liberal twice before.

It's been six years with Justin Trudeau and I'm a little tired of his posturing. He makes really nice promises but doesn't really deliver on them. His platform is just recycling a lot of the things he promised to do the last time around.

Canada deserves change. Singh probably won't form a government but he has a lot of really great policy ideas and, if he gets enough seats in the House of Commons, he'll have a good leg to stand on to make sure some of his policies get implemented.

What is your "ballot box" issue and why?

Affordability. Because I live in Vancouver, I've seen affordability skyrocket. I don't think it's fair that I and other people in my situation have to pay over half of our paycheck just towards rent. When I had family support, I never had to consider the price of rent or groceries or gas. Now that it's something I have to think about on a daily basis, it's really shocking.

The second would probably be climate change. Here in British Columbia, we’ve had some really horrific forest fires. The town of Lytton burned down. The heatwave we just had really showed that everything was changing quickly.

A lot of political commentary recently has made this election about vaccines. It is important, but it's not the smartest trope to make this a pandemic election.

It's been a 35-day campaign, and voters have signalled that there are a wide range of issues influencing how they will cast their vote.

Take a look below at what matters most to Canadian voters. We'll explore these in more detail in the hours ahead.

Canada was not scheduled to hold a nationwide election for another two years - and many Canadians say they're frustrated by the prime minister's decision to go to the polls just two years after the last one.

It has been an unusually busy period of course, not least because of the global pandemic. Here's a quick reminder of some of the key moments in Canadian politics since the last election.

After six years as prime minister Justin Trudeau is a familiar face both in Canada and on the international stage. But under Canada's parliamentary system there are lots of other political parties that voters can choose from.

Here are the leaders of six of the major parties (we'll tell you more about each of them and their policies - as well as their chances of success - throughout the evening):

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