Scotland has six MEPs and in 2009 returned two MEPs from the SNP and Labour and one MEP each from the Liberal Democrats and Conservatives.
A total of 90,398 South Ayrshire voters are eligible to take part in the European Parliament election.
They each have one vote that will be counted alongside others cast across the country to elect the six MEPs for the Scotland electoral region.
Votes are cast for either a political party or an individual candidate standing as an independent – although there are no independent candidates standing for election within Scotland this time. To vote, voters will mark one cross (X) against the party they wish to vote for.
The system used is closed list proportional representation.
In a given region the allocated seats are awarded using a quota system. The quota is the total number of votes received by a party or independent candidate divided by the number of seats already gained in that region +1.
So, for a party with no seats the number of votes received is divided by one, and so stays the same. If the party already has one seat then its number of votes is divided by two, if it has two seats it is divided by three, and so on.
This means that the more seats you have already won, the harder it is to gain extra seats, so the overall allocation of seats is more proportional to the number of votes received.
The first seat that a party wins goes to the first person on its list, the second seat to the second person, and so on, until the party has either not won any more seats or has run out of names on its list. An independent candidate is treated as though he or she were a party with only one name on its list.
Here are the candidates for Scotland.
Scottish National Party
1 IAN HUDGHTON (SNP) Former leader of Angus council. MEP for North East Scotland 1998-1999. MEP for Scotland since 1999.
2 ALYN SMITH (SNP) Born 1973, Glasgow. Educated at Leeds University. Commercial lawyer. MEP for Scotland since 2004.
3 TASMINA AHMED-SHEIKH (SNP) Born in Chelsea. Educated at Edinburgh University. Lawyer and actress. Contested Glasgow Govan 1999 Scottish elections for the Conservatives.
4. Stephen Gethins 5. Toni Giugiano
6. Chris Stephens
1 DAVID MARTIN (Labour) Born 1954, Edinburgh. Educated at Libertson High School. Lothian regional councillor 1982-1984. MEP for Lothian 1984, MEP for Scotland since 1999.
2 CATHERINE STIHLER (Labour) Born 1973, Bellshill. Educated at Coltness High School and St Andrews University. Former researcher for Anne Begg. Contested Angus 1997, Dunfermline and West Fife 2006 by-election. MEP for Scotland since 1999.
3 DEREK MUNN (Labour) Public affairs professional and former special advisor.
4. Katrina Murray 5. Asim Khan
6. Kirsty O`Brien
1 IAN DUNCAN (Conservative) Born in Alyth. Educated at Alyth High School and St Andrews University. Public affairs professional and former Scottish Parliamentary clerk. Contested Aberdeen South 2003 Scottish election.
2 BELINDA DON (Conservative) Born in Birmingham. Educated at Sussex University. Contested Glenrothes 2005, Dundee West 2007, Cowdenbeath, Scotland 2009 European election.
3 NOSHEENA MOBARIK (Conservative) Born in Pakistan. Educated at Strathclyde University. Entrepreneur and Chairwoman of CBI Scotland. Awarded the OBE for services to business in 2004.
4. Jamie Gardiner 5. Iain McGill
6. Stuart McIntyre
1 GEORGE LYON (Liberal Democrat) Born 1956, Rothesay. Educated at Rothesay Academy. Farmer. MEP for Scotland since 2009. MSP for Argyll and Bute 1999-2007.
2 CHRISTINE JARDINE (Liberal Democrat) Educated at Braidfield High School and Glasgow University. Journalist. Contested Aberdeen Donside 2013 by-election.
3 RICHARD BRODIE (Liberal Democrat) Educated at Bathgate Academy and Edinburgh University. Teacher. Dumfries and Galloway councillor since 2008.
4. Jade Holden 5. Siobhan Mathers
6. Euan Davidson
1 DAVID COBURN (UKIP) Born in Glasgow. Businessman. Contested Old Bexley and Sidcup 2010.
2 KEVIN NEWTON (UKIP) Educated at Edinburgh University. Contested Dunfermline West 1997, Clydesdale 2001 for the Conservatives.
3 OTTO INGLIS (UKIP) Businessman. Contested Aberdeen Donside 2013 Holyrood by-election.
4. Denise Baykal 5. Hugh Hatrick
6. Malcolm Mackay
1 MAGGIE CHAPMAN (Green) Born in Zimbabwe. University lecturer. Edinburgh councillor since 2007.
2 CHAS BOOTH (Green) Born in Lincoln. Educated at Edinburgh University. Edinburgh councillor. Contested Scotland region 2004, 2009 European elections. Contested South of Scotland 1999, 2003 Scottish elections.
3. Grace Murray 4. Alastair Whitelaw
5. Anne Thomas 6. Steen Parish
1 KENNETH MCDONALD (BNP)
2 DAVID ORR (BNP).
3. Victoria McKenzie 4. Angus Matthys
5. Paul Stafford 6. Stacey Fleming
1 JOHN FOSTER (No2EU) History professor and international secretary of the Communist Party of Britain. Contested Glasgow Govan 1999 Scottish election, 2001 general election, 2003 Scottish election. Contested Scotland in 2009 European election.
2. Andrew Elliott 3. Murdo Maclean
4. Gail Morrow 5. Brian Smith
6. Richard Veitch
1 JIM DOWSON (Britain First) Former BNP fundraiser and leader of the UK Life League.
2. John Randall 3. Jayda Fransen
4. Geoffrey Clynch 5. Margaret Clynch
6. Jane Shepherd