What does Brexit mean?
It is a word that has become used as a shorthand way of saying the UK leaving the EU - merging the words Britain and exit to get Brexit, in a same way as a possible Greek exit from the euro was dubbed Grexit in the past.
Why is Britain leaving the European Union?
A referendum - a vote in which everyone (or nearly everyone) of voting age can take part - was held on Thursday 23 June, to decide whether the UK should leave or remain in the European Union. Leave won by 52% to 48%. The referendum turnout was 71.8%, with more than 30 million people voting.
What was the breakdown across the UK?
England voted strongly for Brexit, by 53.4% to 46.6%, as did Wales, with Leave getting 52.5% of the vote and Remain 47.5%. Scotland and Northern Ireland both backed staying in the EU. Scotland backed Remain by 62% to 38%, while 55.8% in Northern Ireland voted Remain and 44.2% Leave. See the results in more detail.
What is the European Union?
The European Union - often known as the EU - is an economic and political partnership involving 28 European countries (click here if you want to see the full list). It began after World War Two to foster economic co-operation, with the idea that countries which trade together are more likely to avoid going to war with each other.
It has since grown to become a "single market" allowing goods and people to move around, basically as if the member states were one country.
It has its own currency, the euro, which is used by 19 of the member countries, its own parliament and it now sets rules in a wide range of areas - including on the environment, transport, consumer rights and even things such as mobile phone charges.
What happens now?
Theresa May supported the campaign for Britain to stay in the EU but since becoming prime minister - after her fellow Remain campaigner David Cameron stepped down - she has said she will respect the will of the people and said: "Brexit means Brexit and we're going to make a success of it."
For the UK to leave the EU it has to invoke an agreement called Article 50 of the Lisbon Treaty which gives the two sides two years to agree the terms of the split. Mrs May has said she will not kick off this process before the end of 2016. This means that we will not begin to get a clear idea of what kind of deal the UK will seek from the EU, on trade and immigration, until next year.
Who wanted the UK to stay in the EU?
Then Prime Minister David Cameron was the leading voice in the Remain campaign, after reaching an agreement with other European Union leaders that would have changed the terms of Britain's membership had the country voted to stay in.
He said the deal would give Britain "special" status and help sort out some of the things British people said they didn't like about the EU, like high levels of immigration - but critics said the deal would make little difference.
Sixteen members of Mr Cameron's Cabinet, including the woman who would replace him as PM, Theresa May, also backed staying in. The Conservative Party was split on the issue and officially remained neutral in the campaign. The Labour Party, Scottish National Party, Plaid Cymru, the Green Party and the Liberal Democrats were all in favour of staying in.
US president Barack Obama also wanted Britain to remain in the EU, as did other EU nations such as France and Germany.
What were their reasons for wanting the UK to stay?
Those campaigning for Britain to stay in the EU said it gets a big boost from membership - it makes selling things to other EU countries easier and, they argued, the flow of immigrants, most of whom are young and keen to work, fuels economic growth and helps pay for public services.
They also said Britain's status in the world would be damaged by leaving and that we are more secure as part of the 28 nation club, rather than going it alone.
What about businesses?
Big business - with a few exceptions - tended to be in favour of Britain staying in the EU because it makes it easier for them to move money, people and products around the world.
Given the crucial role of London as a financial centre, there's interest in how many jobs may be lost to other hubs in the EU. Four of the biggest US banks have committed to helping maintain the City's position. But HSBC will move up to 1,000 jobs to Paris, the BBC understands.
Some UK exporters say they've had increased orders or enquiries because of the fall in the value of the pound. Pest control firm Rentokil Initial says it could make £15m extra this year thanks to a weaker currency.
Others are less optimistic. Hilary Jones, a director at UK cosmetics firm Lush said the company was "terrified" about the economic impact. She added that while the firm's Dorset factory would continue to produce goods for the UK market, products for the European market may be made at its new plant in Germany.
