It's the final countdown for Britain, as it closes the chapter on 47 years of European Union (EU) membership on Friday at 11pm.
A countdown clock will be projected on to No 10 and there is a celebration scheduled to take place in Parliament Square, hosted by Nigel Farage it has been reported.
The UK joined the EU in 1973 (when it was known as the European Economic Community) and it will be the first member state to withdraw, since it held its referendum in June 2016. Over 17.4 million people opted for Brexit. This gave the leave side 52%, compared with 48% for remain.
Last Friday, Boris Johnson, who led the vote leave campaign, signed the withdrawal treaty after its passage through parliament, and said the day would signal “the dawn of a new era”.
Following the ratification of Mr Johnson’s withdrawal agreement by Westminster and Brussels, the UK is required to hand over more than £30bn to settle liabilities, guarantee rights to EU expats living in Britain and establish a customs border down the Irish Sea.
The UK will also lose all representation in EU decision-making institutions, but will remain subject to EU rules during a transition period lasting until the end of December.
Speaking ahead of Brexit Day, Mr Corbyn said there would be “different views and feelings” across the country.
“Britain’s place in the world will change. The question is what direction we now take,” he said.
What is the EU? The EU is an economic and political union that has involved Britain and 27 other European countries. It allows free trade, which means goods can move between member countries without any checks or extra charges. The EU also allows free movement of people, to live and work in whichever country they choose.
Former Prime Minister David Cameron, who led the campaign to remain in the EU, called it a very big day for the country, adding that he believed the UK could make a success of the choice that was made.
Brexit Party leader Nigel Farage said: "At last the day comes when we break free. A massive victory for the people against the establishment."
Meanwhile, Ireland is preparing for a series of protests along its border with Britain to mark Brexit day.
Anti-Brexit campaigners are also set to hold demonstrations at Stormont later this afternoon, while supporters of the country’s departure from the EU will celebrate at the gates of Northern Ireland’s devolved government in the evening.
Campaign group Border Communities Against Brexit will hold protests at six points along the border. Union Jacks will also be waved and toasts made by Brexit supporters at Stormont.
Brexit was originally scheduled for 29 March last year but was constantly delayed when MPs rejected a previous withdrawal agreement reached by the EU and former Prime Minister Theresa May.
Mr Johnson was able to get his own deal through Parliament after winning December's general election with a House of Commons majority of 80, on a pledge to "get Brexit done".
In Brussels, the UK flag will be removed from the EU institutions, with one Union flag expected to be handed over to a museum.
European Commission President Ursula von der Leyen paid tribute to UK citizens, thanking them for contributing to the European Union and making it stronger.
She said that it was a story of old friends and new beginnings now and was therefore an emotional day. However, was looking forward to the next stage of negotiations that she hopes will be fair. What happens after Brexit day? After the UK formally leaves the EU on 31 January 2020, there will be months of negotiations to follow.
While the UK has agreed the terms of its EU departure, both sides still need to decide what their future relationship will look like and this will be mapped out during the transition period, with the deadline set for 31 December 2020.
During this 11-month period, the UK will continue to follow all of the EU's rules and its trading relationship will remain the same.
What needs to be negotiated?
As the UK is leaving the single market and customs union at the end of the transition, this 11-month period is meant to give both sides time to discuss a new free trade agreement that allows goods to move around the EU without checks or extra charges.
If a new one cannot be agreed in time, then the UK faces the prospect of having to trade with no deal in place. That would mean taxes on UK goods travelling to the EU and other trade barriers.
Other aspects also to be discussed include data sharing and security, law enforcement, Aviation standards and safety, Access to fishing waters, electricity and gas, as well as licensing and regulation of medicines.
Prime Minister Boris Johnson insists the transition period will not be extended, but the European Commission has warned that the timetable will be extremely challenging. What this has meant for some citizens The number of British citizens who have applied to acquire the nationality of another EU member state has surged since the Brexit referendum, data shows.
Since 2016 more than 350,000 UK citizens have opted to apply for the post-Brexit insurance policy, with some even forfeiting their British passport to retain their EU rights after Brexit.
The 'close historical ties' between Ireland and the UK put the country top of the league of EU passports now held by dual-national Britons. However, there have also been increases in Germany and France, where there has been a rise in naturalisation of British citizens. Some of the changes to look out for UK nationals are being advised to expect new arrangements for travelling to the EU next year. Travel to destinations in the EU, Switzerland, Norway, Iceland or Liechtenstein will change from 1 January 2021.
British citizens are also being advised to always get appropriate travel insurance with healthcare cover before travelling abroad as their European Health Insurance Card (EHIC) card might not be valid in the next 11 months for those who hold one.