With it now certain the Conservative Party will not get an outright majority we are heading for a hung parliament.
The last time this happened was 2010 so at least we have had recent experience of a coalition government, so the lack of a party with a clear majority wouldn’t be quite such an unknown quantity.
But what exactly is a hung parliament?
Quite simply it is the fact no party has enough seats to form an absolute majority in the House of Commons.
When no single party can get enough MPs - the 326 out of 650 seats - to form a majority on its own the Parliament is said to be ‘hung’. That is exactly what happened at the 2010 General Election when the Conservatives and Liberal Democrats shared power.
In the case of a hung parliament, the leader of the party with the most seats is given the opportunity to try to form a government.
From Theresa May’s point of view, she might theoretically attempt a formal coalition with members of the Democratic Unionist Party, one of several smaller groupings potentially in the position of kingmakers.
Equally, she might not create a formal coalition - such as the one between the Liberal Democrats and the Tories in 2010 - but instead come to a more flexible arrangement known as ‘ confidence and supply’.
The ‘confidence’ bit is the promise from the smaller party to support the larger one should there be a vote of no confidence. The ‘supply’ bit means the smaller party would promise to back the larger party’s budget.
But the party leaders could opt to go it alone and try to run a minority government.
Although Britain has faced this scenario before - in reality Theresa May's government still faces huge uncertainty.
How will things will play out?
There are 650 seats in the House of Commons, so an overall majority would mean winning 326.
In reality it's said to be 323 because Northern Ireland's Sinn Fein MPs don't attend Parliament.
Without at least 323 seats, the government won't be able to pass laws if all the other MPs gang up on it.
There are essentially five different ways that the hung parliament can resolve itself - none of them are easily accomplished.
The likelihood of another election pretty quickly will be high, since whoever is in power needs at the bare minimum to be able to pass a budget - and that would require the reliable support of at least one other party.
As Prime Minister, Theresa May would remain in post either until she resigns or there is an agreement about who forms a government.
To do that she - or Jeremy Corbyn - would either need to seek a formal or loose coalition partner, or try to rule as a minority government. The latter arrangement tends to lead to particular levels of instability, with deals being done on a vote-by-vote basis, characterised by horse-trading and bitter argument.
But - and this is a big but - even if the Tories have the highest number of seats, that doesn’t necessarily mean they would get to form a government. Labour could also seek to form a coalition with other parties such as the Lib Dems, SNP or the Greens. They could also try to form a minority government.
Whatever happens, a hung parliament is a recipe for instability. The coalition from 2010 to 2015 is actually remarkable for having stuck together for the entire term, without collapsing into another general election.
Confidence and supply
An informal and less stable version of a coalition - which would involve an ongoing series of negotiations.
'Confidence' means a smaller party supports the government in a vote of no confidence which would boot it out of power.
'Supply' means a smaller party supplies the government with money by voting for, or abstaining on, the budget every year.
But on other votes the government would have less power, so the PM could remain in Number 10 despite losing on key issues.
Also known as government as it goes along - this would be an even looser arrangement between the parties.
It means a government relying on a smaller party's support for some laws but not for others - meaning frantic backroom on any new piece of legislation a government hopes to get through.
In the past, that would have been enough to make a government collapse and force a second election.
But thanks to a 2011 law all Parliaments are fixed for five years.
So a vote-by-vote government would be able to enjoy a more stable environment, but there are still two ways an election can be called before the end of a five year term.
The first is a vote of no confidence, which would be bad PR for a ruling party to back.
The second is if two-thirds of MPs back an early election.
That means - in theory - there could be a deadlock where the PM is in Downing Street despite not being able to pass their budgets.
Labour or the Tories could decide to go it alone and hope their rivals won't risk the country by voting down the Queen's Speech.
Many smaller parties are left-wing, so they'd rather support Labour than the Tories.
The history isn't good though. Tory Prime Minister Stanley Baldwin's 1924 King's Speech was defeated by 72 votes.
He resigned the next morning and Ramsay MacDonald formed the first Labour government, but that only lasted nine months.
When will we know who is our next prime minister?
It could be within days, or it could take weeks. In 2010, Gordon Brown held onto the role for six days as frantic negotiations took place, resigning only when it became clear that the Conservatives and Liberal Democrats had reached agreement on a viable coalition.
Could we have yet another General Election?
There could be a second election if every other attempt at making a government fails.
Most likely this would take place before Christmas and it would cost millions of pounds - both for the taxpayer and for the parties themselves.
It would be the third general election in two years and unlikely to be welcomed by weary voters and businesses crying out for political stability.
Against a background of Brexit negotiations, yet another election campaign would not be an attractive option - but perhaps could be the only one left if the parties are unable to come to an agreement.