British Prime Minister Theresa May has invoked Article 50, marking the official start of the UK's divorce proceedings with the EU 27. Here's a look at what's to come over the next two years of negotiations.
Some nine months since 52 percent of the UK voted in favor of leaving the European Union, British Prime Minister Theresa May on Wednesday triggered Article 50, kicking off two years of talks with the EU 27 to hammer out a Brexit deal.
Here's a look at what's to come:
What exactly is Article 50?
Article 50 is part of the Lisbon Treaty, which was signed by all members of the European Union in December 2007. The plan sets out the rules for any country wishing to leave the EU. Until it became law two years later, there was previously no formal mechanism for a member state to leave the EU.
At just five paragraphs long, Article 50 stipulates that any EU country wishing to quit the EU must notify the European Council. With that task under its belt, the UK will now negotiate its withdrawal with the EU.
Will triggering Article 50 immediately affect the UK's EU membership?
Over the next two years, the UK will remain bound by EU laws and regulations including the single market and freedom of movement. It is also obliged to honor its commitments as a member state, although London gave up its rotating presidency of the European Council - which was scheduled for the second half of 2017 - to concentrate on Brexit negotiations instead.
The UK can also take part in adopting EU acts unrelated to Brexit, but is not allowed to participate in any EU internal discussions about its departure.
Can the UK revoke Article 50?
No country has ever invoked Article 50, therefore there is no precedent as to whether it is reversible. While Theresa May has repeatedly insisted that "Brexit means Brexit," Luxembourg Prime Minister Xavier Bettel previously suggested to British daily "The Independent" that "maybe during the procedure of divorce [the UK] will say 'we love you that much that we are not able to conclude that divorce'."
If Westminster decides to withdraw its application to leave the EU, however, the question could be put to the European Court of Justice.
What is the Brexit schedule?
In light of Theresa May triggering Article 50, the remaining EU 27 are due to meet at a summit on April 29, at which they will set out the arrangements for the UK's departure, "taking account of the framework for its future relationship with the union."
By June at the latest, negotiations between the UK and EU should be underway, with Westminister expected to introduce legislation - the Great Repeal Bill - by fall this year. This will put all existing EU laws into British law, enabling parliament to pick and choose which laws should be kept or revoked.
After a draft deal is agreed, the UK Houses of Parliament, the European Council and the European Parliament will all vote. If the EU and UK keep to schedule, the UK will formally withdraw from the European Union by March 2019.
Who are the negotiators?
There are three main negotiators from the UK who will play pivotal roles in talks with the EU: Brexit Secretary David Davis, Foreign Secretary Boris Johnson and International Trade Secretary Liam Fox. Prime Minister Theresa May, however, will have the final say on any deal.
Representing the EU 27 is the European Commission's chief Brexit negotiator and former French minister Michel Barnier.
What key factors need to be agreed?
Access to the EU single market and trade deals for goods and services between Britain and the remaining member states will be top of the agenda.
The EU's Brexit negotiator Michel Barnier previously said London will have to accept freedom of movement "without exception or nuance" if it wants to retain access to the single market.
Free movement and the living and working rights of the 3 million EU nationals already in the UK, as well as the 1.2 million Brits living in other EU countries, will also need to be agreed upon.
Many EU and UK citizens living abroad have already raised concerns that they will be used as bargaining chips in the process.
How much will Brexit cost the UK?
London can expect an expensive divorce, with European Commission President Jean-Claude Juncker previously warning that "our British friends need to know - and they know it already - that it will not be cut-price or zero-cost."
EU Brexit negotiator and so-called "hardliner" Michel Barnier is reportedly seeking a 60-billion-euro (US$65.4 billion) "exit bill" from UK.
What happens if there's no Brexit deal after two years?
Several analysts expect Brexit negotiations to be a difficult divorce that is likely to take more than the stipulated two years. Should an agreement failed to be reached in that time frame, negotiations can be extended, but only if every EU member state agrees to do so.
Before the UK can leave the EU, any Brexit deal must be approved by a "qualified majority" - i.e. 72 percent of the remaining 27 EU states, representing 65 percent of the population backed by MEPs.
Could the UK leave the EU without a Brexit deal?
In theory, the UK could leave the EU without any agreement and existing treaties and EU law would cease to apply. In that case, however, there might be some acquired rights for EU and UK citizens.
Without any trade deals, this would also see the UK adopting default World Trade Organization tariffs, which are higher than those currently in place.
Would there be a financial penalty for no post-Brexit deal?
An inquiry by the UK's upper house of parliament, the House of Lords, concluded that the UK would be in a "strong" position to walk away from the EU without paying anything if there is no post-Brexit deal.
The Lords warned against leaving without a making a financial contribution, however, as this "would also damage the prospects of reaching friendly agreement on other issues."
Can the UK rejoin the EU after leaving?
Should the UK decide in the future that it wants to rejoin the EU, London would have to re-apply under Article 49 of the Lisbon Treaty, just like any other country wanting to attain EU membership for the first time.