US President Donald Trump is set to arrive in the UK on Thursday for a two-day working visit.
Mr Trump is the 12th sitting US president to make such a trip and will spend time with the Queen and prime minister before flying to Scotland to spend the weekend at his golf resort.
It is his first visit to Britain since winning the 2016 presidential election.
Thousands are expected to protest against the president in London on Thursday and Friday.
BBC diplomatic correspondent James Robbins described the trip as "the most controversial visit ever made by an American president to Britain".
What will he do and who will he meet?
Mr Trump will fly to the UK on Thursday afternoon with First Lady Melania Trump, following a Nato summit in Brussels.
The couple will attend a black-tie dinner on Thursday at Blenheim Palace in Oxfordshire.
Invited guests - including a number of business leaders - will eat dinner to the sounds of the Countess of Wessex's Orchestra, which will play a "series of classic British and American hits", according to a spokeswoman for Prime Minister Theresa May.
After spending Thursday night as a guest of US ambassador Woody Johnson at his London residence, Winfield House, the president will join the prime minister to watch a UK military exercise, before the pair travel to Chequers - the PM's country residence in Buckinghamshire - for bilateral talks.
The president and first lady will then travel to Windsor to meet the Queen on Friday afternoon.
On the final leg of the tour, the couple will fly to Scotland, where they plan to spend the weekend at Mr Trump's Turnberry golf resort. The president's time in Scotland is not counted as part of the working visit.
What is the difference between a working visit and a state visit?
A state visit is a formal visit by a head of state and is normally at the invitation of the Queen, who acts on advice from the government.
The Queen acts as the official host for the duration of the trip, and visitors usually stay at either Buckingham Palace or Windsor Castle.
There is usually a state banquet and a visit to - and speeches at - the Houses of Parliament may be included.
A working visit - like the one Mr Trump is making - may include some of the same activities as a state visit, but there are small differences. For example, on a working visit, the visiting head of state does not address Parliament, nor is their accommodation organised and funded by the UK.
Travel plans on a working visit are also organised and funded by the visiting country.
What protests are planned?
Tens of thousands are expected to protest against the president in London on Thursday and Friday and in Glasgow on Saturday.
Police forces from across the country have been asked to send officers to assist the Metropolitan Police, including 400 from the West Midlands force.
London Mayor Sadiq Khan has granted permission for a giant inflatable figure depicting Mr Trump as a baby to fly over Westminster for two hours on the second day of the president's visit.
Smaller demonstrations are also expected to be held across the UK including Devon, Dundee, Edinburgh, Belfast, Norwich, Manchester, Leeds and Liverpool.
Shaista Aziz, a Labour councillor in Oxford, and one of the organisers of the Together Against Trump protest in London, said the demonstration was about saying "very clearly that we reject the policies of this administration".
What are the security arrangements?
British police have not revealed the exact number of officers required to work during Mr Trump's trip - but the Police Federation has warned the visit will put "unquestionable pressure" on UK police forces.
Forces from across the country have been asked to send thousands of officers to assist with protests. The Home Office said they can be "recompensed by the hosting force".
The Treasury has confirmed it will fund policing costs of up to £5m in Scotland.
The National Police Chiefs' Council said discussions were ongoing about "how the resource requirements of this massive operation will be met" but a spokesman said: "We are confident that forces will continue to maintain local policing services."
What about Trump supporters?
Mr Trump has a number of high profile supporters in the UK - including prominent Brexiteers Nigel Farage and Boris Johnson.
Speaking of Mr Johnson, who resigned as foreign secretary on Monday, Mr Trump said he was a "friend" and he hoped he might find time to speak to him during his visit.
"He's been very, very nice to me, very supportive," he said. "I like Boris Johnson, I've always liked him."
Republicans Overseas UK are organising a rally on Friday to welcome the president while a pub in west London has been renamed The Trump Arms in honour of the visit.
The US Embassy said it was looking forward to Mr Trump's arrival "as an opportunity to highlight the vitality of the special relationship" between the UK and US.