As you read this article, Britons are voting to elect a new Parliament.

Two leaders have a chance of forming the next government. They are incumbent prime minister and Conservative Party leader, Theresa May, and Labour Party leader, Jeremy Corbyn. The polls have tightened in recent weeks, but I believe Theresa May will win a strong governing majority in the House of Commons.

But here's what you should watch for and when you should watch for it.

First up, the exit poll.

When the polls close at 5 p.m. Eastern time (10 p.m. U.K. time), the BBC and other media broadcasters will release exit poll results. The exit polls from the last elections in 2015 and 2010 were quite accurate.

When it comes to actual results, the first indication will come from interviews with candidates at their constituency (district equivalent) counts. In Britain, results are collated at the election announcement sites in each constituency. This means that politicians and their staff are able to walk around exchanging thoughts. Specifically, relaying impressions as to how many ballot paper ticks they have seen next to their names! While this is a crude approach, if we see morose conservative candidates in swing districts, it will indicate an upset and perhaps a national trend.

Of course, official results are the key.

And from 6 p.m. Eastern, constituency results will begin flowing in. At about that time, listen for the results from Conservative target seats like Chester, Ealing, and Halifax (a full list can be found here). If these seats start falling from Labour's column into the Conservative (or Tory) column, Theresa May is in for a good result. Conversely, if supposedly safe conservative seats see reduced majorities, Labour is likely in for a good night.

One caveat here. If you're watching on TV, remember that the British use the traditional colors for the two main parties. Labour, the liberal party, is red. The Conservatives are blue. (This is, by the way, how it was done in the U.S. as recently as 1992.)

By 9 p.m. Eastern, a trend should start developing. At this point we'll know whether the Conservatives are heading for an enlarged majority. And if the results are heading in that direction, expect Theresa May to make a victory statement.

If the Conservatives are winning, it will also be worth watching to see how Jeremy Corbyn responds. In that scenario, he will come under immediate pressure (and I mean immediate) to resign. The vast majority of Labour members of parliament (at least those who are elected) believe he is incapable of leading the party back into power. On the flip side, Corbyn's supporters on the Labour left believe he represents a once-in-a-lifetime opportunity to hold the party to the far left.

Then there's the less likely scenario: Corbyn pulls off a massive upset. If the trend flips to Corbyn's favor, then all bets are off, including for the United States. After all, Corbyn is a fanatical anti-American.

Regardless, it should be a fun night. A lot is at stake and nothing is certain.