The European election will be held this Thursday giving British voters the chance to decide who will represent them in Brussels and Strasbourg.
Apart from the General Election - which will be held next year - it is the only time all 46 million eligible voters in the UK can take part in a ballot.
But how does the voting system work? How many MEPs will Britain elect? And what happened at the last European election?
Here is a helpful guide that answers all of the key questions on the European election.
Can I vote in the European elections?
You have to be a British citizen or a European Union or Commonwealth resident in the UK to be able to vote in the election.
If you are a British citizen abroad you can vote in European and General Elections for up to 15 years after you have left the country.
To be able to vote in the European election you must be registered and the deadline for registering has now passed. The deadlines for voting by post or by proxy have also passed.
The local council usually sends a registration form to most people living in the UK between September and November every year.
You can vote in the 22 May election by going to your nearest polling station - which is often a community centre or school. Your polling card will have the location of the nearest station.
To see if you are registered to vote, call your local elections office or go to www.aboutmyvote.co.uk.
How does the voting system work?
The voting system used in England, Scotland and Wales differs from the one used in Northern Ireland.
A "closed list" proportional representation method is used in England, Scotland and Wales - which means that you cast a vote for a party and not an individual candidate.
The political parties submit a rank list of candidates for each of the 12 regions, with those at the top of the list more likely to gain a seat than those at the bottom.
Seats are allocated to parties in proportion to the amount of votes they received.
In Northern Ireland, the Single Transferable Vote system is used.
This means the voter ranks candidates in order of preference, putting a 1 next to their first choice, a 2 next to their second and so on. The voter may rank as many candidates as they wish.
When will the results be announced?
Votes will start being counted after the polls close in the UK on Thursday.
However, the results can only be declared after 9pm on Sunday 25 May when the last poll in Europe closes.
Residents in the UK and the Netherlands will cast their votes on Thursday, however most of the other countries in Europe will hold the ballot on Sunday - meaning the European election will span four days.
What happened in the last European election?
In 2009, the Conservatives won the European election picking up the biggest share of the vote with 27.7%.
Ukip finished in second place with 16.5% and Labour in third with 15.7%
The Liberal Democrats had 13.7% share of the vote, the Green Party 8.6% and the BNP 6.2%.
How many UK MEPs are there?
The UK has 73 out of the 766 MEPs in the European Parliament.
MEPs are elected in 12 different regions across Britain, they are: East Midlands, East of England, London, North East, North West, Northern Ireland, Scotland, South East, South West, Wales, West Midlands and Yorkshire and Humber.
Northern Ireland will elect three MEPs, Scotland six and Wales 4, compared to London which has eight MEPs.
The amount of MEPs each region has is based on the population of that area.
For more information on the European election, go to the European Parliament's information office in the United Kingdom and About My Vote's websites.