Boris Johnson has announced that he will be stepping down from his role as prime minister in a speech made from Downing Street.
Addressing the nation he said he wanted Britons to "know how sad [he is] to be giving up the best job in the world - but them's the breaks".
However, the PM confirmed he plans to stay in his role until a new leader is appointed.
So what happens next? Professor of Politics at Liverpool University Jon Tonge, answers your questions.
How unprecedented is the situation?
"It is absolutely extraordinary. He ended up as a prime minister without a government.
"When Theresa May stood down, she still had a government in tact and she still had all the ministers. It was her decision that she no longer had the overall confidence of the party, but she didn't lose a government.
"With David Cameron, he quit because he lost the Brexit vote.
"This is unprecedented where basically you had the government, you had everyone just leaving the ship. Boris Johnson was alone at the steering wheel by the end, alone at the tiller.
"We've got to actually replace a government. That's what's unprecedented about all this."
How disruptive will this be to the country?
"It's clearly disruptive because there's been a period of political chaos that we've seen in recent months, and in one sense Boris Johnson's resignation today brings to an end that political chaos, but until a new permanent prime minister and leader of the conservative party is put in place, there is a certain limbo-land that we are entering with a great deal of uncertainty.
"And really, the focus will not be within the conservative party on the business of good government, the focus will be on jockeying for position to be the next leader.
"So there's not going to be a great sense of unity within the Conservative Party. There might be a sense of relief that they've brought down Boris Johnson, who they increasingly felt was a liability, but now, all the respective candidates will be offering favours, seeking preferment, and there'll be a lot of horse trading that goes on now within the Conservative Party rather than a focus upon the business of good government."
How much power does Boris Johnson have as a caretaker prime minister?
"He still has quite a lot of power because although in one sense you're a lame duck prime minister because you don't have much of a shelf life, there's nothing to stop you doing whatever you want to do as prime minister, that you can get through the House of Commons during the period of your caretaker prime ministership.
"He could introduce a whole range of policies. The difficulty with doing that, though, will be that parliament breaks up for the summer in a fortnight's time, so you can't really introduce new legislation or get through new legislation.
"Parliament will be away until September, by which point you're coming to the end of your caretaker prime ministership anyway because the new leader will be in place for sure and by the time the Conservative Party conference in Birmingham in that first week of October."
Can Boris Johnson be ousted as Caretaker prime minister?
"The 1922 committee could oust him as party leader and he would have to resign as prime minister.
"So if he was to behave unsatisfactory in office as a caretaker prime minister, then what could happen is he could be removed from that position by dint of him being no longer leader of the Conservative Party.
"I think that's why the Conservative Party will be anxious to quickly get a move on with the leadership contest, to have the new person in place, because you don't want the caretaker prime minister, whether it be Boris Johnson or anyone else in place for long because they are a lame duck prime ministers, there's not much they can do themselves.
"And so the quicker this is all resolved, the better.
"But, obviously, there has to be a timetable. It will take a few weeks to sort out the leadership contest, allow people to put forward their CVS to other MPs and then put forward, you know, the final two contestants who are left in the ballot, then have to appeal to the party members.
"It will also take a couple of weeks to organise a ballot of all conservative party members. So, you know, speed is of the essence here, but it can't be sorted out instantly who the next leader, the Conservative Party, i.e., the next prime minister will be."
With so many ministers resigning, how will all the vacant positions be filled?
"It is going to be tricky because all those offices of state now need to be refilled.
"The assumption is that most people will be prepared to re-serve on a temporary basis on the Boris Johnson if he remains until the autumn.
"That's an assumption. It will be tested if Boris Johnson does remain in place for a couple of months because not everyone will be willing to serve.
"And it will also be the question of will he be prepared to re-invite certain people who he might feel have let them down, so he may look elsewhere to temporarily fill much of his cabinet and other ministerial positions.
"You can assume that most of the appointments will be those who've already served in the cabinet. But again, there may be some fresh faces brought in.
"We really are in uncharted waters on that because you've never had such a scale of ministerial resignation before."
What happens to the day-to-day running of Government, and will bills which were due to go through Parliament, still progress?
"The bills should still go through because the business of government ought to be unaffected and provided that the ministers can be put back in place to steer those bills through the Commons, then the Conservatives still have a very substantial overall majority within the Commons.
"So while it is not quite business as usual, most of what legislation was going to be railroaded through before the summer recess should still go through."
What will happen to the levelling-up agenda?
"The levelling up agenda was one of the big legacies of Boris Johnson's government, and that will surely carry on apace for two reasons.
"One: There's a lot of money committed to levelling up northern towns and putting lots of money into those towns.
"And secondly, in electoral terms, it makes great sense for the Conservatives because they won some of those constituencies, unexpectedly in many ways given their history, in 2019.
"So that money and that focus will still continue. I think that will still be one of the one of the lasting legacies of the Boris Johnson's government."
Who is favourite to replace Boris Johnson as prime minister?
"I think we should be looking to one of our own North west MPs here, because Ben Wallace has a very strong chance. He's the bookmakers favourite, they have been slashing his odds in recent weeks. He would be in with a very, very strong chance.
"His biggest rivals would be Liz Truss, who has been looking out for this for some time now. I'm not sure that Rishi Sunak will necessarily win, but he may well enter, he'll be a serious contender.
"I'd expect a large number of runners and riders and you can have a ballot today under the rules, but Ben Wallace is where a lot of the smart money lies, and so we may have the first North West prime minister for some time."
When will Boris Johnson's successor be chosen?
"Johnson's successor will be chosen over the summer, sooner rather than later in what will be a series of ballots.
"Depending on how many contestants there are, there'll be a series of rounds.
"The first round is all about survival. You only need the votes of 5% of the parliamentary party, to stay in the contest.
"Then in the next round you need the support of at least 18 MPs to stay in the contest.
"And then it gets pretty brutal because the person who is bottom in subsequent rounds is eliminated until we get down to the final two contestants, then that's the MPs work done.
"The actual leader of those two will be chosen by the members, Conservative Party members. They have the ultimate say in who is the next leader of the Conservative Party."
What do we now call Boris Johnson officially? Is he caretaker prime minister or prime minister?
"We still call him 'prime minister' because there's nothing in the British Constitution that actually formalises the position of caretaker, you're either prime minister or you're not.
"It's a matter for the Conservative Party that Boris Johnson is only a caretaker prime minister, by dint of the fact that he is resigned.
"That, of course, struck fear into the hearts of some Conservatives this morning because what they're saying is you know, he may try and carry on, and just say, well, you know, there might be another crisis looming of some sort and, actually, I'm still prime minister, I want to carry on.
"With any other leader you wouldn't worry about that, but with Boris Johnson, because of his unpredictability, that is a possibility, I suppose."
Will Boris still be prime minister in November?
"No, he can't still be the prime minister in November because when he goes to see the Queen to tender his resignation, he will either quit then or more likely say that he will carry on as the caretaker prime minister until a specified date.
"Once he's notified the monarch of that date, there would obviously be an obligation upon Boris Johnson to actually formally step aside then.
"And then the leader, the newly elected leader of the Conservative Party will become the Prime Minister, it has to be the leader of the largest party, the party that can command the majority in parliament.
"So Boris Johnson will be able to renege on that commitment, even if he wished to do so.
"There are some people, like I notice Dominic Cummings, his former adviser, who are saying don't trust Boris Johnson, he might try and cling on to office.
"It's inconceivable that his party would let him, they would simply vote no confidence in him again and under the rules of the party you would have to step down in that case."