Ministers have arrived in Downing Street on the day the UK triggers the process to leave the EU.
At the moment, there are more questions than answers.
The fate of EU nationals in the UK and UK nationals in the EU is one of the most pressing.
Prime Minister Theresa May signed the formal request to break with Brussels in the Cabinet room on Tuesday.
It gives official notice of leaving, under Article 50 of the Lisbon Treaty.
The British Ambassador to the EU Sir Tim Barrow will deliver the letter to the European Council president Donald Tusk in Brussels at 1230 UK time.
The decision follows a referendum last June in which the UK voted to leave the EU.
There were signs of optimism when markets opened across Europe, despite the concerns prompted by Brexit Day.
The CAC 40 opened 0.42% up at 5.067,23 points.
In Frankfurt, the Dax gained 0.59% while the FTSE in London was up 0.3% on opening.
The eurozone’s EuroStoxx was up 0.17% on opening while the FTSEEurofirst 300 gained 0.43% and the Stoxx 600 0.12%.
Your questions about Brexit answered