Following is the chronology of Brexit as the UK is set to leave the European Union at 2300 GMT on Friday, more than three and a half years since the country voted for it in a referendum in 2016.
January 23, 2013: Prime Minister David Cameron promises an in-out referendum on EU membership if his Conservative Party wins the 2015 General Election.
May 7, 2015: The Conservatives make sweeping gains over the Labour Party and secure a majority in the House of Commons.
June 23, 2016: The UK votes in a crucial referendum to leave the EU with 52 per cent of the public supporting Brexit. David Cameron, resign as prime minister.
July 13, 2016 : Theresa May wins the Conservative Party leadership contest and becomes prime minister
March 29, 2017 : May sends a letter to European Council President Donald Tusk, triggering Article 50. It sets the date for the UK's departure in two years' time: March 29, 2019.
April 18, 2017 : May announces a snap general election in the UK, to be held on June 8.
June 8, 2017: May loses her Commons majority after her election gamble backfires.
July 17, 2017: Brexit talks officially get underway in Brussels between EU and UK negotiators.
March 19, 2018: The UK and EU publish a draft agreement on Britain's withdrawal. But the agreement is not totally agreed.
July 6, 2018: Prime Minister May unveils to her Cabinet her much-awaited Chequers plan.
July 8, 2018: The UK's Brexit minister David Davis resigns in protest. Foreign Secretary Boris Johnson follows suit.
November 15 2018: Dominic Raab resigns as Brexit Secretary.
November 25, 2018: The 27 European Union leaders endorse the Brexit deal.
December 13, 2018: Prime Minister May survives a vote of confidence in her leadership of the Conservative Party.
January 15, 2019: MPs reject May's Brexit plans by an emphatic 432 votes to 202 in a historic vote.
March 12, 2019: MPs again reject the Government's Brexit deal by 391 votes to 242.
March 20, 2019: May asks the EU to delay Brexit from March 29 until June 30.
March 29, 2019: MPs reject May's Withdrawal Agreement by 286 votes to 344, majority 58, on the day when the UK was due to leave the European Union.
April 10, 2019: EU apress on a flexible extension to Brexit is agreed until October 31.
May 24, 2019: May announces she is standing down as Tory party leader on June 7.
June 7, 2019: May officially steps down as Tory leader.
July 23 2019: Boris Johnson is elected as leader of the Conservative Party and becomes the UK's new Prime Minister.
August 28, 2019: The UK Parliament is prorogued, or suspended, for five weeks, upon advice given to Queen Elizabeth II by Johnson's government.
September 3, 2019: 21 rebel Conservative MPs vote against the government in protest at its Brexit strategy of driving the UK towards an exit from the EU by October 31.
October 3, 2019: The UK government sends a new Brexit plan to Brussels.
October 17, 2019: The UK and EU announce dramatically that they have struck a new Brexit deal, ahead of a Brussels summit.
October 19, 2019: At a special Saturday sitting, British MPs withhold their approval for the deal until laws implementing Brexit are in place.
October 22, 2019: Johnson puts Brexit legislation on “pause”, citing MPs' obstacles.
October 28, 2019: The EU agrees to offer the UK a Brexit “flextension” until January 31.
October 29, 2019: The House of Commons approves a general election on December 12.
December 12, 2019: Prime Minister Johnson's Conservatives wins General Elections and gain an 80-seat majority in the Commons.
January 23, 2020: The UK's EU Withdrawal bill becomes law, after a relatively smooth passage through Parliament.
January 29, 2020: The European Parliament approves the Brexit divorce deal under which the UK will leave the EU on 2300 GMT on January 31.