Today is Britain's last day as a member of the European Union after joining in 1973.
It has been a tumultuous period of our history - and that is before we get into the 1318 days since Britain voted to leave the EU narrowly on June 23 2016.
But today is the day that Britain officially leaves the EU - even if not all that much is going to change immediately because of the transition period.
So when is Brexit happening?
The UK was originally due to leave the EU on March 29, 2019 - but since then out membership has been extended three times while negotiations about the withdrawal agreement were ongoing.
Boris Johnson had pledged a "do or die" Brexit by October 31, 2019, but was forced to request a "flextension" after a No Deal was taken off the table.
But after the Withdrawal Agreement was agreed by both the EU and Parliament we will leave today January 21.
What time will the UK leave the EU?
Brexit will become official at 11pm on Friday, January 31.
This is because it is midnight in Brussels.
A countdown clock will be projected onto 10 Downing Street from 10pm, followed by a red, white and blue light display.
What is the transition period and when does it end?
The transition will last until 31 December 2020 and in this time the UK will remain in both the EU customs union and single market.
That means until the transition period ends a lot of things won't change - including travelling to and from the EU, freedom of movement, EU-UK trade.
