It is arguably the most important decision the British public has faced in decades.
And, for many people, the debate around the country's membership of the European Union is also one of the most confusing.
Below, we answer a few basic questions ahead of the big vote in June.
What is a referendum?
It is a vote involving all citizens in which the winner is the side which takes more than half of all votes cast.
When is the referendum?
Thursday, June 23. Polling stations are open from 7am to 10pm.
What is the question?
Polling cards will contain the following: "Should the United Kingdom remain a member of the European Union or leave the European Union?"
Who can vote?
British, Irish and Commonwealth citizens over 18 and who are resident in the United Kingdom, along with UK nationals living overseas who have been on the UK electoral register in the past 15 years. Commonwealth citizens of Gibraltar are also eligible. EU citizens living in the UK are barred from taking part.
How do you vote?
Registered voters will receive a card saying when voting takes place and at what location. Once at the polling station, there will be booths containing a pencil. Voters will put an X in a box of their choice and then drop the paper into a ballot box.
What if I am on holiday?
Votes can be cast by post. You will need to apply by June 8.
To apply for a postal vote go to:www.kirklees.gov.uk/beta/voting-and-elections/postal-voting.aspx
When will the results be made public?
Votes cast in Kirklees will be counted at Cathedral House, Huddersfield, after the polls close at 10pm on June 23. All the votes are collated and the overall result will be announced at Manchester Town Hall.