Brexit Is Happening: Here’s What You Need To Know About It

Update : The BBC is reporting that after 43 years, the United Kingdom has voted to part ways with the European Union. It appears to be a narrow victory for the referendum, with London and Scotland voting to remain and rural areas in England and Wales voting to leave. The Associated Press reports that the news has sent the British pound plunging to a 31-year low as the results become clear.

Update: Millions of voters are heading to the polls today to determine whether the United Kingdom will remain a part of the European Union. Ahead, a look at the referendum and what it could mean. This story was originally published on June 17, 2016. Voters in the United Kingdom are poised to make one of the most important decisions in a generation on June 23, when a public referendum will decide whether the U.K. leaves the European Union. Campaigning by those for and against a so-called "British Exit, or "Brexit," was in full force until yesterday, when a young female lawmaker was brutally murdered while meeting with her constituents. Labour MP Jo Cox, 41, a mother of two who represented Batley and Spen in West Yorkshire, was stabbed and shot by an attacker on Thursday. She later died from her wounds. A 52-year-old man who allegedly sympathized with the neo-Nazi National Alliance, according to the Southern Poverty Law Center, has been arrested in connection with her death. Many people, including British Prime Minister David Cameron and Labour Party Leader Jeremy Corbyn, have expressed their condolences and support for Cox's family following her death.

The killing occurred just a week before U.K. citizens will head to the polls. The “yes” or “no” vote gives the British population, who haven’t weighed in on their E.U. membership in more than 40 years, a direct say in the matter. And in this public referendum, a simple majority wins. It’s all happening because Britain's Prime Minister promised — after political pressure — that he’d give the electorate a say if he won the general election in 2015. British voters' choices are likely to have a big impact on the rest of the world, too: The population of the E.U. is more than 500 million, or about 7.3% of the world's population as a whole. Any British, Northern Irish, Welsh, and Commonwealth citizens older than 18 years of age, along with U.K. nationals living overseas who are on the electoral register, can cast a ballot. The vote could go either way, as the latest polls show the country to be pretty evenly divided on the issue. Everyone from the Church of England, which has offered a prayer for the referendum, to the Cornish Pasty Association seems to have an opinion on the matter. (And in case you're unfamiliar, Cornish pasties are like England's empanadas — and the association is voting to stay). But what would Brexit mean for the U.K., Europe, and the U.S.? Refinery29 breaks down the basics and what's really at stake.

European Union 101
The E.U. came about after World War II, when several European nations wanted to come up with a plan to help ensure that they would never again be at war with each other. The first step was economic interdependence, because countries that traded with one another would both have something to lose if conflict broke out — at least, that was the thought. The European Economic Community was formed in 1957 with six countries. But it wasn’t until 1973 that the U.K. joined. The scope of the E.U., through various treaties, includes internal policies as well as external relations such as trade, security, and migration. Today there are 28 members of the E.U., with several more “candidate” countries that hope to join — such as Turkey and Serbia. "Britain is different, no question," than other E.U. countries, New York Times London bureau chief Steven Erlanger said. "It has always seen itself as apart from the Continent — in government, law, and habits — though obviously tied to it, too, for trade and security and much else, especially in these globalized days… [But] having won both world wars, with American help to be sure, Britain also doesn't feel the need or the comfort other European countries have in the protections of shared and limited sovereignty."

Who wants to stay and why?
U.K. Prime Minister Cameron is chief among those who would like the U.K. to remain an E.U. member. Many of the political parties agree with him, as does the Chancellor of the Exchequer George Osborne. The Treasury believes that upon an exit, the U.K.'s GDP would be 6.2% lower and families would be worse off to the tune of about U.S. $6,200 a year. Voters are concerned about immigration and security, too. British Secretary of State for Defence Michael Fallon believes that shared intelligence with Europe benefits the U.K.

And more than 250 celebrities, including Benedict Cumberbatch and Keira Knightley, signed a letter in support of remaining, stating: "From the smallest gallery to the biggest blockbuster, many of us have worked on projects that would never have happened without vital E.U. funding or by collaborating across borders. Britain is not just stronger in Europe, it is more imaginative and more creative, and our global creative success would be severely weakened by walking away." The Britain Stronger in Europe campaign highlights their concerns about leaving the E.U. here.

Who is in favor of Brexit and why?
Justice Minister Michael Gove, the right-wing U.K. Independence Party, along with the former London mayor Boris Johnson, are among the biggest voices arguing the U.K. should go its own way. Johnson has told voters: "We were being asked to remain in an E.U. that was unabashed, unrepentant, undemocratic and, above all, unreformed." Johnson and others like him want to be free of E.U. regulations and to take back British taxpayers’ dollars to spend on other things like healthcare and education. The for-leaving camp also thinks it would be better for U.K. security. Richard Dearlove, a former head of the British Secret Intelligence Service, has argued that the U.K. would benefit if it had greater control over immigration coming from the E.U. "Britain is Europe’s leader in intelligence and security matters and gives much more than it gets in return," Dearlove wrote in Prospect magazine. The divorce with the E.U. would start with a two-year negotiation about the new conditions of the relationship — and it’s “unlikely to be amicable," Erlanger wrote in The New York Times.

The Vote Leave campaign for exiting the E.U. breaks down more concerns about staying here.

What does the rest of Europe and the U.S. think?
While the rest of Europe has become skeptical of the Brussels-based union, most countries think that if Britain does choose to leave, it would be hurtful to the 28-member bloc, according to the Pew Research Center. The countries feeling the strongest love for the institution are Poland and Hungary, where 72% and 61% of the population, respectively, are in favor of the E.U., while in Spain, France, and Greece those numbers drop to 47%, 38%, and 27%, respectively. Millennial voters between 18 and 34 years old are more inclined to like the E.U. than those aged 50 and older. Similarly, those on the left of the political spectrum are more favorable toward the body than those on the right, Pew found. Discontent with the E.U. is associated with its handling of economic problems as well as its management of the refugee crisis. Overwhelming majorities in all 10 of the countries surveyed reported dislike for the decisions made on the refugee crisis. For his part, President Barack Obama has spoken up in favor of staying in, writing in The Telegraph: "The European Union doesn’t moderate British influence — it magnifies it…the U.S. and the world need your outsized influence to continue — including within Europe."

But ultimately, in this heated campaign, facts are playing only a small role. "It is deeply political — hence emotional — and having, sometimes, only a vague connection to the facts. Both sides are now operating on fear — of economic risk for Remain, and of ‘uncontrolled immigration’ for Leave. Other arguments seem to have exhausted themselves, and it's gotten quite repetitive, and also personal," Erlanger said. Correction: An earlier version of this story incorrectly stated that the Conservative government believes that upon an exit, the U.K.'s GDP would be 6.2% lower and families would be worse off to the tune of about U.S. $6,200 a year. The study cited shows it is the Treasury that believes this. Refinery29 regrets the error.