The UK is leaving the European Union, more than three-and-a-half years since the referendum result.
There are a number of Brexit celebrations planned for the evening of January 31, including a street party in Parliament Square.
Union Jacks will be flown around Parliament Square and a clock counting down the minutes to 11pm will be projected on Downing Street.
Below is everything you need to know about 'Brexit Day'.
When is Brexit?
The UK is officially leaving the European Union at 11pm on Friday, January 31.
However, the end of January is not the end of the Brexit process.
The transition period which runs until the end of 2020 is aimed at giving time for the Government and Brussels to thrash out the future relationship between the UK and EU.
Although both sides agreed to the timetable, the EU has already suggested that it would be impossible for the kind of trade deal Boris Johnson wants, where the UK would be free to diverge significantly from Brussels’ rules.
The Prime Minister has said it is “epically likely” that a deal will be agreed in time.
How will it be marked across the UK?
50p coin from the Royal Mint
Chancellor Sajid Javid originally ordered production of the celebratory coins in advance of the original departure date of October 31.
But the Brexit delay meant about a million coins had to be melted down and the metal put aside until a new exit date was confirmed.
The new coin, which entered circulation on January 31, reads: “Peace, prosperity and friendship with all nations.”
About three million Brexit coins entered circulation around the UK on Friday, with a further seven million to be added later in the year.
As part of the launch of the coin, the Royal Mint opened its doors for 24 hours to let people strike their own commemorative Brexit coins.
Big Ben chimes
Despite demands from campaigners, Big Ben will not bong for Brexit.
Organisers of a campaign to pay for Big Ben to ring out to mark Brexit admitted defeat after failing to persuade the House of Commons authorities to allow the bell to ring.
The appeal raised £272,770, fuelled by Boris Johnson’s suggestion that “we are working up a plan so people can bung a bob for a Big Ben bong”.
But no such plan existed and the House of Commons Commission estimated that the cost of bringing the bell back into use could be as much as £500,000.
The fundraising drive, led by Stand Up 4 Brexit and Tory MP Mark Francois on the GoFundMe website, was cancelled at noon on Monday, with the money raised now being donated to the Help for Heroes military charity.
Leave means Leave party
The Leave Means Leave Brexit Celebration at Parliament Square will feature “singalong hymns” and speeches from Mr Farage, Ann Widdecombe and Julia Hartley-Brewer.
Wetherspoons boss Tim Martin and Brexit Party chairman Richard Tice are also expected to speak at the rally, which takes place between 9pm and 11.15pm.
The gathered crowds will count down to 11pm before rounding off the celebrations with the national anthem.
Earlier in the day at Parliament Square, the civil rights group New Europeans is to host a discussion about the rights of EU citizens in the UK.
This will be followed by a candlelit vigil outside Europe House on Smith Square, Westminster, in the evening.
The Government is to mark the event with a “commemorative light display” in Downing Street just before 11pm, with a countdown clock projected on to its black bricks from 10pm.
Union Jack flags will line Parliament Square and The Mall, while Government buildings in Whitehall will be lit up in red, white and blue colours throughout the evening.
Festival of Brexit
Martin Green, formerly in charge of the Olympic opening ceremonies, has been given the task of planning a £120m festival to take place over 2022.
The festival was first suggested during Theresa May's government as a showcase for “the UK’s unique strengths in creativity and innovation”.
Critics have branded the showcase as "divisive" and the "Festival of Brexit".
A programme for the festival will be announced at the end of 2021.