Exit polls are expected to be published at 10 p.m. local time tonight (5 p.m. ET), when voting ends.
The results should come out Friday morning.
Here's what you should know about contenders Prime Minister Theresa May and Labour leader Jeremy Corbyn.
Theresa May is a British politician who has served as prime minister of the U.K. and leader of the Conservative Party since 2016. She says Brexit is an opportunity for Brits and aims to tackle terrorism.
May went to the polls this morning to cast her vote along with her husband.
Labour leader Jeremy Corbyn is a British politician who has served as leader of the Labour Party and leader of the opposition since 2015. Corbyn's platform is to help the "The Many" by investing in communities.