A quick guide to the key points of the 2019 European Parliament elections in the UK.
The Brexit Party was the clear winner, but the Lib Dems and the Green Party also made significant gains.
The Conservatives have come in fifth place, with less than 10% of the vote.
Voting took place against a backdrop of paralysis at Westminster over Brexit, and BBC political editor Laura Kuenssberg said the two biggest parties - Conservatives and Labour - had been damaged by their various contortions on the issue.
They were beaten by rivals - on both the Leave and Remain sides - who offered clarity while they have tried to find nuanced ways through, she added.
Polling expert Sir John Curtice said the results demonstrated how polarised the country was on Brexit - and how evenly support is split between Remain and Leave.
How have the parties performed?
- Nigel Farage's Brexit Party - launched just six weeks ago - received the highest share of the vote in nine of the 11 regions declared so far. Overall it has taken 32% of the vote
- The pro-EU Lib Dems have also made gains, taking second place with 20%. They did best in Gibraltar (77% of the vote), Richmond upon Thames (52%) and Kingston upon Thames (47%)
- The Green Party recorded its best performance since 1989, taking 36% of the vote in Brighton and Hove and 35% in Bristol
- The Conservative Party was widely rejected by the electorate, with its worst performance since 1832
- The Labour Party fell to third place overall - fifth in Scotland - and is on course to end up with less than 15% of the vote, an even worse performance than in 2009
- UKIP, the winning party in the 2014 election, failed to take any seats
- Newly-formed pro-European party Change UK also didn't win a seat
- The SNP dominated in Scotland, with 38% of the vote
- Plaid Cymru came second in Wales, beating Labour
The Brexit Party was the biggest winner in England, with 26 MEPs elected. The party's leader, Nigel Farage, is once again an MEP in the South East.
However, the Lib Dems topped the poll in London, taking three out of the eight seats in the region.
The result in Wales
Wales has elected two MEPs from The Brexit Party, one from Plaid Cymru and one from Labour.
The Brexit Party topped the poll in 19 out of the 22 council areas.
BBC Wales political editor Felicity Evans said it had been an "extraordinarily bad" night for Welsh Labour - a party that has won every Wales-wide poll (except one) for a century.
The SNP comfortably topped the poll in the Euro elections in Scotland, amid a collapse in support for Scottish Labour.
The SNP took 38% of the vote, increasing its number of seats from two to three.
The Brexit Party were second with nearly 15% percent and one seat. The Liberal Democrats and Tories took one seat each. Labour came fifth and lost both the Euro seats they held.
BBC Scotland political reporter Philip Sim said it has been a good night for the SNP and a "decent night" for The Brexit Party, which improved on UKIP's previous performance in Scotland.
Northern Ireland's result
Northern Ireland's count does not begin until Monday, with most results expected on Tuesday.
What about the rest of Europe?
The big centre-right and centre-left blocs in the European Parliament have lost their combined majority amid an increase in support for liberals, Greens and nationalists.
Populists gained ground in some countries but fell short of the very significant gains some had predicted.
In Germany, both major centrist parties - including Angela Merkel's Christian Democrats - suffered, while in France, President Emmanuel Macron's Renaissance alliance was defeated by the far-right National Rally of Marine Le Pen.
- The Conservatives came third in the Royal Borough of Windsor and Maidenhead - part of Theresa May's constituency - with 13.4%
- Even in Hillingdon, where Boris Johnson has his seat, they were relegated to fourth place with 12.4%
- The Labour Party came second in the borough of Islington, in Jeremy Corbyn's constituency with 28.5%
- Alastair Campbell, PM Tony Blair's former spin doctor and prominent member of the People's Vote campaign for another referendum, said for the first time in his life he had voted for the Lib Dems
- Change UK's well-known names - such as Rachel Johnson, the sister of Boris, and Gavin Esler, the former BBC News presenter - failed to get elected
- UKIP's leader Gerard Batten lost his seat
- Controversial UKIP candidate, Carl Benjamin - who refused to apologise for saying he "wouldn't even rape" Labour MP Jess Phillips - was not elected
- Former English Defence League leader Tommy Robinson, who ran as an independent candidate in the North West under his real name Stephen Yaxley-Lennon, also failed to win a seat
- The South East region has - confusingly - elected two MEPs with the same name: Alexandra Phillips. One Alexandra is a Brexit Party MEP, the other represents the Greens
Anti-Brexit parties - those in favour of another referendum - collectively took about 40% of the vote, compared with 35% for the two parties in favour of leaving the EU without a deal.
Turnout in the UK was just below 37%. This is on course to be the second highest in any European election.
Places that voted most strongly to Remain in the referendum saw turnout increase more compared with the last election in 2014 than places which voted most heavily for Leave.
In Europe, turnout was the highest for 20 years, at 51%.