BREAKING: Counting Begins.

Polls closed Thursday in what's shaping up to be one of the closest elections in British history.

The votes are in, and results from an exit poll run jointly by the BBC, Sky News and ITN project Conservatives in the lead and gaining seats.

Even though the final tally isn't in, one thing is clear: This is an election you should be paying attention to, even if you're not one of the millions of Brits who cast a ballot.

It's an election that could reshape the country's global role for years. Britain's relationships with the European Union, NATO and the United States are hanging in the balance. And the Scottish National Party might get a major boost at the polls that could fuel a fresh push for Scottish independence.

Prime Minister David Cameron has called it "the biggest and most important election in a generation." 

As he campaigned this week, he touted what he said was the country's economic recovery under his Conservative leadership. "I've now laid my brick," he said, claiming that the big payoff is yet to come for Britain as the country builds on the work he's done.

He's also said that if re-elected, he'll hold a referendum on Britain's membership in the European Union.

On the other side, the Labour Party's Ed Miliband -- who prides himself in standing up to U.S. influence -- is promising higher taxes on the wealthy and protection of Britain's public health system.

"We're fighting for a Britain where we reward the hard work of every working person," he said this week, "not just those who get the six figure bonuses in our country."

But the days of two-party politics are long gone. Leading up to this election, the growing popularity of fringe parties on the left and right has kept the race ultratight.

All the opinion polls since Parliament broke up in March have pointed to the Conservatives and Labour being neck and neck, with each party's predicted share well within the margin of polling error.

The election is not a vote for who will be Prime Minister, but its outcome will determine who leads the United Kingdom going forward and whether Cameron keeps the top job.

A total of 650 members of Parliament will be elected, representing constituencies across England, Scotland, Wales and Northern Ireland.

Whichever political party has the most members of Parliament elected will be invited by Queen Elizabeth II to form a government. If there's no clear winner, then a minority or coalition government may be formed.