Weary voters in the United Kingdom go to the polls today for the third time in five years.

Australians following the UK election count on Friday morning will be watching a process that is familiar in broad outline, but strangely alien in detail.

When Australian democracy was born in the mid-19th century, its electoral system shared a common ancestor with Britain's.

But 170 years later, elections in Australia have evolved into a separate species.

Meanwhile the UK's electoral processes are essentially unchanged since 1918, the first British election to be held on a single day for polling.

As it was a century ago, United Kingdom election nights are about individual constituency declarations, revealed one by one, in an overnight marathon of counting.

How the vote and results will unfold

Voting is voluntary at UK elections and uses simple majority or 'first past the post' voting.

Voters in the UK will head to polling stations which open at 7am and finally close at 10pm. ( Reuters: Toby Melville )

There are no preferences, and no progressive figures are released.

Counting is completed as soon as the polls close, and the candidate with the most votes is declared winner on the night.

By convention, elections have been held on a Thursday since 1935. Polling stations are open from 7:00am until 10:00pm.

In Australia votes are counted in polling places, but this is not the process in the UK.

Instead, ballot boxes are transported unopened, along with associated paperwork, to a central counting centre.

Ballots are not counted in polling stations. Instead they are rushed into counting centres. ( Reuters: Ed Sykes )

The process takes time, which is why it takes several hours before constituencies start to declare.

The delay in official results means that exit polls play a greater role in UK election coverage.

For the past decade, media organisations have pooled their resources to conduct a single exit poll supervised by the master of UK elections, Professor Sir John Curtice of Strathclyde University.

The exit poll is released on the stroke of 10:00pm as polls close in the UK.

It will then be at least an hour before there are any official results, and around three hours before the vast bulk of constituencies begin to declare.

In 2010 the constituency of Houghton and Sunderland South declared at 10:54pm and was first again in 2015, declaring at 10:48pm.

In 2017 only 15 of the 650 constituencies declared within the first three hours.

Throughout election night, broadcasters cross to key constituency declarations.

UK politicians — including prime ministers — stand on a stage while the result in their constituency is announced. ( Reuters: Toby Melville )

In the presence of the candidate, a quaint on-stage ceremony unfolds where the names of candidates and votes received are read out and the winner declared duly elected.

The numbers revealed on stage are the only result available for each constituency.

There are no progressive results released and polling place results are not available.

How Brexit has transformed UK voting blocs

British politics has traditionally been dominated by class: working class constituencies voting Labour, the shires and more affluent parts of the cities voting Conservatives.

Prime Minister Boris Johnson and Labour Opposition Leader Jeremy Corbyn are going head to head in the general election. ( Reuters: Toby Melville )

The traditional patterns have been upended by the 2016 referendum on leaving the European Union.

Both major parties were split by Brexit into 'Leave' and 'Remain' factions.

Affluent urban seats that voted to remain in the European Union are unhappy with the Conservatives.

Traditional working class seats that voted to leave the European Union have been annoyed by the Labour Party's part in delaying Brexit.

Majority government requires 326 seats in the 650 seats in the House of Commons.

The fact the Speaker and Deputy Speakers don't vote in divisions, and that Northern Ireland's Sinn Fein MPs do not take their seats, means that a government can still survive with fewer than 326 seats.

Theresa May called the 2017 election in the hope of winning a big majority so she could sideline anti-EU members of her party.

Returned with only 317 members, she was forced to negotiate with the Democratic Unionists, and left vulnerable to attacks from the pro-Leave wing of the Conservatives.

The fractious nature of the House of Commons since 2017 has forced Boris Johnson to follow Theresa May's tactic in calling an early election in the hope of gaining a majority to finally deliver on Brexit.

Mr Johnson will want a secure majority and more united Conservative Party as the formal achievement of Brexit in January is only the start of an extended negotiation for a new trade arrangement with the EU.

As well as losing seats in Scotland, the Conservatives will be challenged by the Liberal Democrats and independents in southern England.

The SNP's Nicola Sturgeon and the Liberal Democrats' Jo Swinson could be powerbrokers in the event of a hung Parliament. ( Reuters: Hannah McKay )

Some of their opponents are former Conservative MPs banished in the early days of Boris Johnson's Prime Ministership.

Helping Mr Johnson is his Labour opponent Jeremy Corbyn, the most unpopular leader of a political party in the history of UK polling.

Mr Corbyn campaigned well on austerity and the National Health Service in 2017, and has focused on the same issues in 2019.

However, in Boris Johnson he faces a far stronger campaigner than Theresa May.

Boris Johnson is hoping to win a majority in the UK Parliament so he can push through his Brexit plan. ( Reuters: Ben Stansall )

The fate of government could be determined by the so-called 'red wall', a string of Leave-voting but traditionally Labour-held seats running from North Wales through Lancashire and Cheshire to southern Yorkshire.

That includes seats like Wrexham in Wales, Crewe and Nantwich in Cheshire, and, further north, Workington in Cumbria.

All are traditional Labour-voting constituencies that backed leaving the EU and where Jeremy Corbyn is viewed as having little electoral appeal.

Polls in the final weeks of the campaign have narrowed, but still point to a Conservative majority.

Now the wait is on for the exit poll at 10:00pm on Election Night.

If that doesn't indicate a clear majority, the slow wait for individual constituency declarations will begin.