The United Kingdom is having a European Union referendum on Thursday (June 23). What are they voting on and  how will the vote impact on the UK and beyond? BBC World News presenter Philippa Thomas offers a quick explainer on the referendum.

What are the people of the UK voting on?

Should the UK remain a member of the EU or leave the EU? After polling stations close on Thursday, all the votes will be added up. That will give two totals for Leave or Remain. The side that gets higher than 50 per cent of the vote wins.

What is the EU? 

It is a partnership of 28 European countries. It is based around the idea of a “single market” allowing goods and people to move around freely.  It has a currency, the euro, now used by 19 of its members, although the UK has kept the pound sterling.  

But it is important to remember that the EU is political as well as economic. It has its own Parliament, and it sets rules on a lot of aspects of everyday life.

Hasn’t the UK voted on this before? Why do they want to revisit a decision made 40 years ago? 

Because it was forty years ago! If you’re a Brit who was born after 1957 — like me — you haven’t had your say on something that could affect much of your life — from the job market to the cost of your holidays to the quality of the air that you breathe. 

Also, membership of the “Common Market” that our parents voted on back in June 1975, is very different to membership of today’s “European Union”.  Then, the British were voting to continue their new membership of the EEC, the nine-state European Economic Community. Today, we are talking about our part in a 28 member union with its own Parliament and currency.  

This is the first time Britons have voted on whether we want to be part of a community of more than 500 million people, stretching from Ireland to Estonia. So it is very relevant to have these arguments about whether by being “in”, we are gaining friends and influence or losing valuable independence. What do we think and which of those factors matters to us more? 

Where does the term “Brexit” come from? 

This is a shorthand term for a British Exit from the EU. It first popped up four years ago, after all the agonising about Grexit, the possibility of Greece leaving the euro zone. And there’s more — other variations include Fixit, as Finland debated earlier this year whether it should hold its own referendum.

How are members of the same government supporting different sides? 

A lot of people are confused to see the UK Prime Minister David Cameron campaigning to Remain, and members of his own party — such as former London Mayor Boris Johnson — or even his own Cabinet ministers — such as Justice Secretary Michael Gove — urging voters to Leave. 

But Mr Cameron’s decision to allow even the ministers he has appointed to speak freely on this, reflects the political reality: The governing Conservatives are deeply divided on whether EU membership is good for us. They have been for decades. 

The main opposition Labour party is clearly in the Remain camp, although a few Labour MPs are calling for the UK to leave the EU.

But it would be too simplistic to try to sum up the EU debate as a “left-right” struggle. It is so easy on so many big issues to say “the Left thinks this and the Right thinks that”. But not here. So you hear some Conservatives such as Mr Winston Churchill’s grandson, Member of Parliament Nicholas Soames, urging voters to stay with a European project created out of the desire to stop France and Germany ever going to war again. And you hear powerful left wing voices arguing that the EU favours big corporations and damages national democracies. 

So there is no simple divide, no easy political shorthand. Let’s just say, in the run up to June 23, much of normal Westminster politics is suspended. 

Will the result mean a change of UK government or leadership? 

In short, no. This is a one line question about one thing only: Should the UK remain in or leave the EU.

To give you a slightly longer answer, this is a bitter campaign that has divided both main parties — especially the governing Conservatives. If voters decide that the UK should leave the EU, many will ask whether Mr Cameron — who led the campaign to remain — should stay on as party leader and as Prime Minister. But there is nothing about the vote on Thursday that automatically or legally triggers any change of leadership. 

Will it be a clear result? 

In short, yes. It is either stay or go. 

But you know I am going to tell you that the real answer is — it is complicated. If the UK stays, for example, what happens to the deal that Mr Cameron made with his fellow EU leaders in February on limiting welfare payments to migrants? 

If the UK is to leave, how will that be organised? Will Britain stay in the Single Market? What sort of trading, treaties and alliances with the outside world will the UK negotiate? The Leave campaign suggests that a UK-EU Treaty could be wrapped up within two years. Many Remain campaigners say it could take much longer than that. 

At the moment there is no shortage of proposed answers, but many of them come as competing theories. 

What about the different nations of the UK? 

This is a UK-wide vote, and I do not want to generalise because there are different political forces at play. 

It is fair to say that north of the border, the Scottish political establishment is much more clearly in favour of staying in the EU — and that was reflected by a formal vote in the Scottish Parliament last month. But public opinion here too is divided. 

It is worth noting — if the UK does vote to leave the EU, there could well be political pressure at Edinburgh for a second referendum on whether Scotland in turn would want to leave the UK. 

Most leading Welsh politicians are backing the campaign to stay, though the polls show public opinion is more divided.

And there is a great deal at stake for Northern Ireland. If we leave the EU, there could be new customs checks across the border between north and south, a land border between a UK that is “out” and an Irish Republic that is very definitely inside the EU. 

BBC World News will provide rolling coverage from Westminster and Brussels, as well as economic and market reactions around the world to the outcome of the referendum, in a special day of live broadcasts on Friday (June 24).