Atrocities near Parliament, in Manchester and at London Bridge have left Britain on high alert. Polling stations opened across Britain on Thursday amid heightened security worries following a series of terror attacks in what one senior police official described as "unprecedented times".
Labour leader Mr Corbyn grinned broadly and gave the thumbs-up to reporters and party workers as he voted in Islington, north London.
"I have little confidence in anybody", said voter Simon Bolton, 41, in east London.
Sophie Allison, riding her horse Splash, rides out of the driveway of a private residence, set up as a Polling Station, near Reading, west of London, on June 8, 2017.
Headline rates for sterling, hit two-week highs in morning trade in London after the latest polls.
It is an election that was called unexpectedly and that has unfolded unexpectedly.
Voting ends at 10pm BST.
Both main parties were on the defencive after Saturday's van and knife attack in the heart of London.More news: Apple announces iOS 11
Two of the men, aged 27 and 29, were held on suspicion of preparing acts of terrorism while the third was detained over suspected drugs offences. Normal campaigning was interrupted by both attacks. She became prime minister through a Conservative Party leadership contest when predecessor David Cameron resigned after the referendum, and an early election would give her the chance to gain a personal mandate from voters.
Should a hung parliament or Labour majority seem likely at this point, sterling is expected to head south. May's mantra throughout the campaign was that she was the person to provide "strong and stable" leadership.
"May is hoping for a stronger majority to help her negotiate Britain's exit from the European Union, but her once-strong lead shrank during the campaign". The staunchly pro-EU Liberal Democrats hope to scoop up voters opposed to leaving the bloc.
By 6am a clear victor should be known with numerous results declared. Five more years of a Tory government, five more years of austerity, five more years of cuts.
Stone said he could not recall an election where anti-Semitism emerged as such a prominent issue since Labour depicted then-Conservative leader Michael Howard - who is Jewish - in posters as Fagin from Oliver's Twist, that prompted concern among some Jewish voters. The last thing many wanted was another divisive campaign.
Meanwhile, veteran left-winger Corbyn, who was written off as a no-hoper by most political analysts, surprised on the upside with a policy-rich campaign that drew large, fervent crowds to his events - although sceptics say his appeal in the broader electorate is limited.
Labour propose to build a fairer society through policies such as increasing tax for the richest 5 percent, boosting workers' rights, scrapping university tuition fees and investing 250 billion pounds in infrastructure.
Opposition Labour Party leader Jeremy Corbyn in his final rally claimed he had reshaped British politics.
"Wouldn't it be great if on Friday we woke up to. a Labour government that will be a government for all of our communities across the whole of the country, to deliver that social justice that we all crave?" he said. "Hope that it doesn't have to be like this, that inequality can be tackled, that austerity can be ended, that you can stand up to the elites and the cynics".