It could decide both the fate of the U.K.'s departure from the European Union

and the future of the world's fifth-largest economy.

So, how does Britain's voting system work?

In a general election, the U.K. is divided into 650 local areas called parliamentary constituencies,

each of which is represented by one member of parliament, or MP, in the House of Commons.

Constituencies vary in size geographically, but typically each will have between 60,000 and 80,000 voters.

All British citizens resident in the country and aged 18 years old or over on December 12

will be able to cast their ballot, with some 46 million people reportedly registered to vote.

Voters choose one person from a list of candidates to represent their local area,

and the candidate that receives the most votes wins.

All of the elected MPs then enter parliament to sit in the House of Commons

and represent the people in their constituency.

The political party that secures the most MPs is then invited by the Queen to form the government.

An absolute majority in parliament is 326 seats,

although the number for a working majority is slightly lower in practice.

That's because lawmakers elected for Sinn Fein in Northern Ireland actively abstain from

taking up their seats in Westminster, since the party rejects Britain's claim to sovereignty over Ireland.

So for example, in the 2017 election, seven Sinn Fein MPs were elected.

This effectively lowered the threshold for a majority to 322.

If there is a clear result when polls close at 10pm on election day,

we can expect to see opposition leaders conceding to the winner.

However, if recent history is to repeat itself and no party secures a majority,

the election could bring about another hung parliament.

In June 2017, a shock exit poll showed Theresa May's ruling Conservative party

had failed to return a parliamentary majority.

This is completely catastrophic for The Conservatives and for Theresa May.

It forced the prime minister to strike a deal with the Northern Irish Democratic Unionist Party, or DUP,

in order to secure a working majority in the House of Commons.

If there is no clear winner this time around, parties could look to create a formal alliance together.

That way, they could bolster their chances of securing enough votes to pass laws in parliament.

As the incumbent, Boris Johnson would get first try to form a government.

Instead of Theresa May's agreement with the DUP, he could try to secure a formal coalition arrangement,

which is what happened in 2010 between the Conservatives and the Liberal Democrats.

... and work together in the national interest.

If Johnson is unable to form a government, he could resign and recommend the leader of

the largest opposition party be given a chance to form the executive.

As is typical with major national parties in campaign mode ahead of the general election,

they have all suggested they would not be willing to work together to form a government.

Most countries around the world use a proportional voting system,

meaning that a party that wins half of the total vote share also wins half of the seats in parliament.

But, not in the U.K.

The voting system used in Westminster is known as first-past-the-post.

A term used in horse racing; it signifies that the contest is effectively over

once a candidate receives the largest number of votes for their local area.

Essentially, it's winner takes all.

The same voting system is used in Canada and India,

as well as many Caribbean and African states.

Advocates of first-past-the-post say it is a simple and familiar process

which usually delivers a one-party government.

It allows that party to implement their plans over the duration of the parliament.

First-past-the-post certainly has its critics, with many quick to point out

that the winning MP usually receives less than half of the vote.

In most constituencies, the majority of people actually end up voting against

the winning candidate rather than for them.

MPs are sometimes elected on a vote share as low as 35%,

leaving the losing parties with 65% of the vote.

The winning party is also usually elected by less than half of the electorate.

In fact, of the 21 general elections between 1935 and 2017, the majority of voters

only voted for parties that formed a government on two separate occasions.

Smaller parties often hit out at the first-past-the-post voting system too,

arguing they do not gain fair representation.

In 2015, the U.K. Independence Party, led at the time by Brexit proponent Nigel Farage,

received 12.6% of the vote, but this only returned one MP.

It's also argued that the first-past-the-post voting system encourages what's known as tactical voting.

Take so-called 'safe seats' for instance.

If you're a voter that lives in a constituency that usually returns a Labour MP for example,

you may feel there is little point in backing a Conservative candidate

because they are unlikely to be elected.

When this happens, and it happens a lot,

voters may choose to vote against a candidate they dislike rather than for one they prefer.

Or they might not vote at all.

Around two-thirds of constituencies in the U.K. are considered safe seats.

In 2011, the British public was given a chance to change Westminster's voting system

with the Alternative Vote referendum, but the electorate overwhelmingly rejected this option.

The vote on December 12 is much more likely to usher in a government

led by either the Conservative Party's Boris Johnson or the Labour party's Jeremy Corbyn.

The incumbent has sought to frame the vote as “a Brexit election”.

We're going to get Brexit done!

With each of the major national parties offering markedly different

visions of how best to resolve the U.K.'s long-running constitutional crisis.

Johnson, who had promised to deliver Brexit by October 31 “come what may, do or die,”

demanded a general election after parliament frustrated his attempts

to ratify his last-minute divorce deal with the EU.

As the leader of the center-right Conservatives, Johnson said that if his party wins,

he will get lawmakers to ratify his Brexit divorce deal before the end of January.

By comparison, Corbyn's Labour party has indicated they would need slightly longer to resolve Brexit.

The center-left opposition has said it will negotiate a new withdrawal agreement

with the bloc within six months of the election.

Labour would then seek to hold a national referendum on whether to leave on the terms it has agreed,

which it says will mean maintaining very close ties between Britain and the EU, or to remain.

Corbyn, the veteran socialist leader of Labour, has said he will stay neutral in such a referendum

We can't go on forever being divided by how people voted in 2016.

He's argued it's right to try to appeal to both the 52% of people who voted Brexit

and the 48% of people that voted to remain.

Meanwhile, the pro EU Liberal Democrats are trying to woo voters away from bigger parties

by promising to scrap Brexit altogether.

Jo Swinson, the leader of the centrist party, has said the fast-approaching vote

is “a moment for seismic change.”

Almost all politicians were in agreement that a pre-Christmas election was necessary

to try to break a cycle of inaction over Brexit.

And major parties are now scrambling to attract weary voters in a bid to end years of political crisis.

Thanks for watching! If there are any other topics you think we should be covering please do let us know.

See you next time.