By Dave Howard and Chris Mason
Newsbeat politics reporter and BBC Europe correspondent
The European Union elections take place on 4 June but what do you know about the EU? Find out how the EU functions, what happens during a European Union election and how the European Parliament affects people's lives in the UK.
How does the European Union work?
Think of the EU like a triangle.
In one corner of the triangle are the national governments. They meet regularly in Brussels and they're the most powerful part of the European Union.
In the next corner is what's known as the European Commission. It's unelected. It dreams up ideas for new European laws and makes sure existing ones get obeyed.
In the third corner of the triangle is the only directly elected bit - the European Parliament. Every five years we get a say on who sits there, and the elected Euro MPs then get a say on what gets made into law.
We're talking about a huge area here. Give me an idea of the numbers involved?
These are the biggest trans-national elections in history.
375 million voters in 27 countries can choose from around 9,000 candidates.
736 Euro MPs will be elected; including 59 in England, six in Scotland, four in Wales and three in Northern Ireland.
How does the European Parliament affect my life?
Euro MPs don't set our taxes or decide if a local school or hospital's going to close, but they do have a big influence on how we live our lives.
They make decisions in Brussels that directly affect our jobs, our family lives, the healthcare we get, rules about recycling and energy.
MEPs recently passed a law significantly cutting the cost of texting from abroad. They've also banned seal products being imported into Europe; and they've stopped airlines from using misleading adverts that suggest we can fly to Spain for 50p.
OK - so now I understand why I might want to use my vote. But how do elections work at European level?
At UK General Elections we're used to the so-called "first past the post" system.
Areas or counties, with about 70,000 people in them, elect one single MP - the person who gets the most votes in that area.
In European elections, they use a system called "proportional representation" (often shortened to 'PR'). The voting areas are often vast.
On the plus side, there's a better match up between the share of the vote parties get and the number of seats they get.
On the downside, every region has between three and 10 MEPs, which goes some way to explain why many people haven't got a clue who represents them in the European Parliament.