Brexit Is Finally Happening — Here's What You Need To Know

Update: British Prime Minister Theresa May has officially told the European Council that Britain wishes to leave the European Union.

Tim Barrow, Britain's top envoy to the EU, delivered May's letter personally to Donald Tusk, president of the European Council. The notice was in accordance with Article 50 of the Lisbon Treaty.

"Today the government acts on the democratic will of the British people," May told lawmakers in the House of Commons, according to the Associated Press. "This is an historic moment from which there can be no turning back."

Last week, British Prime Minister Theresa May informed the European council that on Wednesday, March 29, she would finally invoke an agreement called Article 50, signaling that the United Kingdom will begin the process of leaving the European Union.

This is the moment everyone has been waiting for ever since the Brexit vote stunned the entire world last summer. But what does it really mean for Britain?

Ahead, we've broken down everything you need to know about this process and how it could impact people both in the U.K. and abroad.

The term "Brexit" was formed by merging the words "Britain" and "exit."

Last June, the United Kingdom held a public referendum to decide whether the country would leave the European Union after 43 years. The "Leave" vote won with 51.9% of the votes, while "Remain" obtained 48.1%.

By leaving the 28-country bloc, the U.K. would be giving up everything from participating in the EU parliament, to observing laws that apply to every member of the union, and even to shared mobile phone charges.

The main reasons Brexit supporters wanted to withdraw from the EU were the economy, national security, and the ability for the U.K. to have independence over its laws. Pro-Brexit advocates wanted to be free of the EU's trade regulations and to stop being affected by fluctuations in the Euro. (The U.K. is one of the nine EU countries that don't use the euro as currency.) They also argued that by leaving the European Union, Britain would have more control over immigration issues and the nation's border security.

Those who argued in favor of the remaining in the EU made opposing arguments to those same issues. The Treasury said that after Brexit the U.K.'s GDP would be 6.2% lower and families would be deeply affected. And the Remain camp also argued that when it came to national and border security, Britain benefitted from sharing intelligence with the rest of the countries in the union.

Article 50 of the Lisbon Treaty is the formal mechanism through which a country can leave the European Union. The agreement became law in 2009. The article is pretty short and it states that any country wishing to leave the EU must notify the European Council. Afterwards, a negotiation between the member state and the union will begin. It's expected that talks between Britain and the EU will begin in the summer.

No. The U.K. and the European Union have two years to come to an agreement. This period of time could be extended if the remaining 27 countries unanimously agree to it. The departing country, in this case Britain, is prohibited from partaking in the internal conversations of the remaining members of the union.

Chancellor Philip Hammond had previously said it could take up to six years for the the country to conclude the exit negotiations.

After Article 50 is triggered, the U.K. will still abide by the EU's laws, but won't be able to take part in the decision-making process.

In one word: complicated. The U.K. and the European Union will have to disentangle 43 years of treaties and agreements. There's also no precedent for this process, because no other country has ever left the union. It will take a long time for everything to fall into place. The post-Brexit trade deal in particular is expected to be the most complex and debated part of the negotiations, because it will require the unanimous approval of over 30 national and regional parliaments across all of Europe.

Prime Minister May said that if no deal is reached with the European Union, the U.K. would still leave. In her mind, it would be better for the country to leave without a deal in place than to agree to a bad deal.

That could be possible. Article 50 has never been put to the test before, and the author seems to think that it's legally possible for it to be revoked.

"It is not irrevocable. You can change your mind while the process is going on. During that period, if a country were to decide, actually we don't want to leave after all, everybody would be very cross about it being a waste of time," Lord Kerr told the BBC last fall.

He added, "They might try to extract a political price but legally they couldn't insist that you leave."

However, it would be up to the European Court of Justice to determine whether the process could be stopped or not.

It's unclear what will happen to EU nationals who are currently living in the U.K., or to U.K. citizens who are living in other countries that belong to the European Union. Their fates will depend largely on the outcome of negotiations over the next two years. It's possible that if the U.K. imposes work restrictions on EU nationals, other countries could reciprocate and make British employees apply for work visas.

The only group of EU nationals whose rights are "safe" are those who have lived in the U.K. for five years and currently have the right to permanent residence.

It's technically possible, but it would be a long and difficult process for Britain. They would have to start from scratch and enter ascension talks with the EU from a disadvantaged position. All the other members of the union would have to agree to the U.K. rejoining. And they wouldn't have leverage for conditions such as keeping the Pound as their currency, because every new member of the EU is required to adopt the Euro. However, this conversation is highly theoretical, and we'll have to wait and see how it all shakes out.