The next presidential debate between Hillary Clinton and Donald Trump will take place on Wednesday, October 19, 2016. This will be the final of three planned debates between the two presidential nominees before the election, and it will be moderated by Chris Wallace of Fox News.

For decades now, these debates have been the marquee events of the general election season, since they’re often the only time the two major party nominees come face to face. Indeed, the first debate between Clinton and Trump in late September drew over 80 million viewers — and seems to have boosted Hillary Clinton in the polls.

The impact of the second debate, combined with Trump's leaked tape scandal, isn't yet clear. But the big picture is that there's a whole lot at stake.

When are the debates?

Every remaining debate will run from 9 to 10:30 pm Eastern, and here's the full schedule.

Monday, September 26, 2016: First presidential debate. Transcript here.

Tuesday, October 4, 2016: Vice presidential debate between Tim Kaine and Mike Pence. Transcript here.

Sunday, October 9, 2016: Second presidential debate. Transcript here.

Wednesday, October 19, 2016: Third presidential debate in Las Vegas, Nevada, at the University of Nevada, moderated by Fox News’ Chris Wallace.

That final debate will take place just two weeks and six days before Election Day (Tuesday, November 8).

Do the debates matter?

Political scientists Robert Erikson and Christopher Wlezien have written that according to their research, the debates "clearly do not have major impact to the same degree as party conventions," and they've found that the polls tend to shift by only a few percentage points during the debates season. That could be important in a close race (and this race now looks close!), but a massive change is unlikely.

Now, historically, the debates have sometimes produced big short-term swings in the polls. Mitt Romney, for instance, took the lead over President Obama after what was judged to be a strong first debate in 2012. And Hillary Clinton appears to have gotten a bounce of a few points after this year's first debate.

Yet historically, those effects often haven't last very long. Sometimes a debate bounce will just fade, or sometimes it will be canceled out by a subsequent debate that helps the other major candidate (as it was for Romney).

And in other years, the person judged to be the "winner" of the debates doesn’t get much of a bounce at all — as in 2004, when polls showed voters thought John Kerry won all three debates but President Bush remained in the lead.

Overall. we don't yet know whether Clinton's debate bounce from the first debate will prove to be durable, or something cancelled out by the second debate and other events — but we do know Trump still has one more opportunity to make a better impression. Check out a fuller rundown of the political science evidence on the impact of presidential debates here.

Watch: How presidential debates are won and lost