The Prime Minister has resigned, forced out following a series of scandals engulfing his government.
But Boris Johnson doesn’t intend to go straight away – he wants to remain in Number Ten until a new leader of the Conservative Party is elected.
The process can take a while – the last contest took two months – after which Johnson will visit the Queen to tell her he is standing down.
She will then formally appoint his successor and the UK will have a new Prime Minister.
How does the leadership contest work?
Candidates must win support from eight Tory MPs to get themselves on the initial shortlist.
Once nominations close, the MPs will hold a series of votes until only two candidates are remaining.
They will then start campaigning, before party members around the UK vote for their favourite.
Whoever gets most votes wins and becomes Prime Minister.
Does there have to be a general election?
No, that decision is in the hands of the new PM.
The last two residents of No 10 did ask the country to assert their authority after taking over in the middle of a parliamentary term.
Theresa May lost her majority but stayed in power in 2016, before Johnson won a landslide after taking over in 2019.