Here is a guide on when to expect key results on UK election night.
Polling stations close in the UK, followed immediately by the publication of a BBC, ITV and Sky News exit poll. It will offer the first clues as to how the night will unfold. At each of the past few elections, the exit poll has produced a very accurate projection of the actual result.
Two constituencies are racing to be first to declare: Houghton & Sunderland South and Newcastle-upon-Tyne Central. Both results are expected around 11pm and both are safe Labour seats, so it will be the change in Labour's share of the vote - and the size of a potential swing to the Conservatives - that will be most useful in providing further clues to the overall election result. There should also be the first indications of turnout.
Four more safe Labour seats are likely to have declared, all in northeast England. Again, look out for any evidence of a change in Labour's vote share and a possible swing to the Conservatives.
Workington could be the first seat of the night to change hands. If the Conservatives take it from Labour, Boris Johnson might be on course for a comfortable majority in the new parliament. If Labour holds on, the overall result could be a lot closer.
North Down should be the first result of the night from Northern Ireland. It is a seat formerly held by the Independent MP Sylvia Hermon, and being targeted at this election by the DUP, the Ulster Unionists and the Alliance Party.
Results will start to pick up. If Labour is doing well, it may take Carlisle, Putney, Thurrock and Vale of Glamorgan from the Conservatives. If Labour is doing badly, it could see the likes of Stockton South, Wrexham and West Bromwich West being gained by the Tories.
The first results will come from Scottish seats being defended by the SNP, such as Dunbartonshire West and Lanark & Hamilton East.
A flood of results is expected. Former Tory MP Dominic Grieve is hoping to win Beaconsfield as an Independent. The Lib Dems will want to hold Brecon & Radnorshire, which they gained from the Conservatives earlier in the year, and retake Nick Clegg's former seat of Sheffield Hallam from Labour.
Labour might defeat Iain Duncan Smith in Chingford & Woodford Green, while the Lib Dems could take Esher & Walton from Dominic Raab. The result is due from Dartford, a bellwether seat since 1964.
The SNP have their eyes on the Tory seats of Ochil & Perthshire South and Stirling. If Labour is having a good night, they will be making gains in places such as Telford and Worcester.
If the Tories are performing well, they will hope to take seats like Great Grimsby (a Labour seat since 1945), Bishop Auckland (Labour seat since 1935) and Don Valley (Labour since 1922).
Jeremy Corbyn's result in Islington North is due, as is Jo Swinson's result in Dunbartonshire East.
In Foyle, Sinn Féin will be hoping to keep their marginal seat but SDLP leader Colum Eastwood will be trying to regain it for his party.
Over half of the results will be in, and the overall trend of the night should be clear. Labour targets such as Harrow East, Loughborough and Milton Keynes South will declare, likewise Lib Dem targets like St Albans and Cheltenham. All are being defended by the Conservatives.
Labour will hope to hold the ultra-marginal seats of Canterbury and Crewe & Nantwich, as well as Ipswich, Lincoln and Rother Valley, which are all Tory targets.
Plaid Cymru is defending Ceredigion against challenges from the Lib Dems, Labour and the Tories.
The SNP will hope to hold Fife North East and with a larger margin than they managed in 2017, when they had a majority of just two.
The Ulster Unionists are hoping to take Fermanagh & South Tyrone from Sinn Féin.
Anna Soubry should have discovered whether she has been able to hold Broxtowe for the Change party.
Boris Johnson should also know whether he is safely back in Uxbridge & South Ruislip, where he won only a slim majority over Labour in 2017.
Kensington, another of Labour's ultra-marginals, should have declared by now, although the result in 2017 needed several recounts and was not confirmed until nearly 24 hours after polls closed.
The Lib Dems have a chance to make a couple of gains from the Tories in Cheadle and Hazel Grove, while the SNP could do likewise in Gordon.
Dennis Skinner could be unseated by the Conservatives in Bolsover, and other Labour seats at risk include Ashfield, Colne Valley and Keighley.
Results should have slowed to a trickle.
A handful of seats in London could deliver some late upsets: Labour is hoping to take Chipping Barnet and Hendon from the Conservatives, while the Liberal Democrats could unseat the Tories in Finchley & Golders Green and Richmond Park.
The Lib Dems are also eyeing the Tory seat of Wells.
Caroline Lucas will have discovered if she has been re-elected as the Green MP for Brighton Pavilion.
There is the possibility of some very late gains for the Lib Dems in southwest England, who are hoping to defeat the Tories in Cornwall North, St Austell & Newquay and St Ives.
Recounts could delay some of the declarations from earlier, but every seat is due to begin counting overnight so there is a good chance all 650 results will be in by mid-morning.
Follow all the developments from Northern Ireland and Britain through the night on rte.ie/news, the News Now app, Facebook, Twitter, and Instagram. RTÉ Prime Time will bring the exit poll results from 10pm Thursday, and an election special will air on RTÉ One and RTÉ News Now from 11pm until 4am.