The House of Commons has 650 seats of which, one party needs to win 326 to form a government.
Exit polls predict the Conservatives will win 315 seats, Labour 261, Scottish Nationalists 35 and the Liberal Democrats 12.
We explain what could happen next:
UK Elections result in hung parliament
May can try forming government, must survive confidence motion
Incumbent PM May will be given first preference to try forming a government, either as a minority or through a coalition with other parties.
If this happens, her Conservative government will need to survive a motion of confidence in the House of Commons, probably after parliament opens on June 19.
If she succeeds, May will be able to continue as PM.
If May fails, Corbyn will have to try forming government
However, if May can't form a government or survive a confidence motion, she would have to resign as PM to Queen Elizabeth II.
The Queen would then likely invite the opposition Labour party leader Jeremy Corbyn to similarly try forming the government.
If neither government survives a confidence motion, the parliament would be dissolved and fresh elections would be held.
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