Wednesday night marks the final clash between Democratic presidential nominee Hillary Clinton and Republican nominee Donald Trump
It's the last chance for the two candidates to make their closing arguments to a national stage before Election Day.
Here's everything you need to know about the showdown.
What time does it start?
Just like the previous two presidential and one vice presidential debates, this debate begins at 9 p.m (American Time). It's scheduled for 90 minutes with no commercial breaks.
Where is it?
The debate will be held at the University of Nevada, Las Vegas. It'll be the university's first presidential debate but it has hosted presidential guests in the past. Most recently, President Barack Obama gave a speech at the school in 2012 to talk about student loans.
Who is moderating?
Fox News' Chris Wallace, the host of "Fox News Sunday," will moderate the event. It's Wallace's first general election debate, but he co-moderated Fox's three GOP primary debates this cycle.
Candidates have tangled over the role of the moderator at each of the previous two debates. Trump initially gave NBC News' Lester Holt strong marks for his first debate moderating, but he soon reversed course to blast him as biased.
CNN's Anderson Cooper and ABC News' Martha Raddatz didn't even make it out of the debate before Trump criticized them. He shot back after an interruption from the moderators to question why they were not interrupting Clinton too.
Clinton's team has called on moderators to play a role in fact-checking the participants, but Trump wants a passive moderator. Wallace said during last weekend's "Fox News Sunday" he wanted to be nothing more than a "timekeeper."
What topics will they cover?
Wallace has chosen six topics for the debate-debt and entitlements; immigration; the economy; the Supreme Court; foreign hot spots; and fitness to be president.
The final topic is a particularly interesting one, considering Clinton's repeatedly attacks on Trump's temperament, and Trump's criticisms of Clinton's family foundation and her controversial email set-up as secretary of State.
What are the rules?
The debate will have six 15-minute segments for each topic.
It's a return to the standard debate style, with each candidate behind a podium, instead of the town-hall style from earlier this month.
Who is carrying it?
The debate will air on all of the broadcast and cable news networks as well as C-SPAN, Univision and PBS.
It will also be streamed online by a variety of other outlets.
What's the size of the debate audience?
The debate will be held at UNLV's Thomas & Mack Center, the 19,000-plus seat auditorium that hosts the Runnin' Rebels basketball team less than two miles from the Vegas Strip.
The debate commission did not announce how many people would be in the debate audience, but there were 1,000 in the audience at the smaller arena at New York's Hofstra University.
Some UNLV students will be able to attend through a lottery system-Quartz reported that students will have to meet a GPA requirement to enter. The campaigns and political parties will also receive tickets-Trump's campaign has already announced it will bring along a vocal critic of Clinton, the mother of a State Department employee whose son died in the 2012 Benghazi attacks.