On the ABC News app? Click HERE to watch this interactive video.
But were they always telling the truth? How often did Trump and Clinton spin facts to fit their arguments?
ABC News fact-checked some of the most noteworthy claims made in the debate:
Fact-check No. 1: Trump claims he did not say global warming is hoax perpetrated by the Chinese
Clinton: "Because we will be making investments where we can grow the economy. Take clean energy. Some country is going to be the clean energy superpower of the 21st century. Donald thinks that climate change is a hoax, perpetrated by the Chinese. I think it's real."
Trump: "I did not. I did not. I do not say that. I do not say that."
Fact-check No. 2: Clinton has been fighting ISIS her "entire adult life"
Trump: "See, you are telling the enemy everything you want to do. No wonder you have been, no wonder you have been fighting ISIS your entire adult life."
Explanation: ISIS has its origins in al-Qaeda in Iraq, the Sunni insurgent group founded in 2004 after the U.S. invasion and occupation of Iraq. In 2013, the group rebranded itself as the Islamic State in Iraq and al-Sham (ISIS) and shifted operations to include Syria, where the civil war enabled its growth and resurgence. This occurred after Clinton had finished serving as secretary of state. Clinton is 68 years old and turned 18 in 1965, almost 51 years ago.
Fact-check No. 3: Trump started his business with $14 million borrowed from his father
Clinton: "Donald was very fortunate in his life, and that's all to his benefit. He started his business with $14 million, borrowed from his father, and he really believes that the more you help wealthy people, the better off we'll be and that everything will work out from there. I don't buy that. I have a different experience. My father was a small-business man. He worked really hard."
Grade: Yes and no
Explanation: Trump claims that his business grew out of a $1 million loan from his father in 1975. But a casino license disclosure from 1985 shows that in the late 1970s and early 1980s Trump took $14 million in loans from his father and his father's properties, according to The Wall Street Journal.
Fact-check No. 4: Trump said Clinton called the Trans-Pacific Partnership the "gold standard" of trade deals
Trump: "You called it the gold standard. You called it the gold standard of trade deals. You said it's the finest deal you have ever seen, and then you heard what I said about it, and all of a sudden you were against it."
Grade: Yes and no.
Explanation: Clinton said the TPP "sets the gold standard" and has used many other glowing terms to describe the agreement, but she did not say it was the "finest deal" she has ever seen. While Clinton served as secretary of state, she promoted the TPP well after negotiations began in 2010, saying in 2012 in Australia that it "sets the gold standard in trade agreements to open free, transparent, fair trade, the kind of environment that has the rule of law and a level playing field." She used many other complimentary words — including "exciting," "innovative," "ambitious," "groundbreaking," "cutting edge," "high quality" and "high standard" — according to a compilation by the fact-checking site PolitiFact — but there are no records of her saying it was "the greatest deal" she had "ever seen." Furthermore, Clinton began to moderate her position on the TPP as she began preparing her second presidential bid, culminating with a full renunciation of it during a 2015 PBS interview, in which she said, "As of today, I am not in favor of what I have learned about it." It is worth noting that she was not serving as secretary of state when the deal was finalized. Clinton countered Trump in Monday's debate by trying to clarify that she said she had "hoped" TPP would set a gold standard for trade. But it is clear from her 2012 remarks that at least one time in public, she declared that it "set" the gold standard, with no qualifiers.
Fact-check No. 5: Trump says he has not suggested that he would negotiate down the national debt
Clinton: "And when we talk about your business, you've taken business bankruptcy six times. There are a lot of great businesspeople that have never taken bankruptcy once. You call yourself the king of debt. You talk about leverage. You even at one time suggested that you would try to negotiate down the ..."
Trump: "Wrong, wrong."
Clinton: "... national debt of the United States. Well, sometimes there's not a direct transfer of skills from business to government, but sometimes what happened in business would be really bad for government."
Grade: Yes and no
Explanation: Trump suggested he would renegotiate the national debt in an interview with CNBC on May 5, 2016, but then said in The Wall Street Journal on May 10, 2016 that he would buy back U.S. debt at a discount. "I'm only saying you can buy back … I'm saying if interest rates go up, you can buy debt at a discount on the market — just on the market. You just buy back debt on — at a discount," he told the Journal.
Fact-check No. 6: "Hillary Clinton also fought it" — insisting Barack Obama is not a natural-born citizen, which is the basis of the birther movement
Trump: "Well nobody was pressing it. Nobody was caring much about it. I figured you'd ask the question tonight, of course. But nobody was caring much about it. But I was the one that got him to produce the birth certificate, and I think I did a good job. Secretary Clinton also fought it, I mean, you know — now, everybody in mainstream is going to say, oh, that's not true. Look, it's true."
Explanation: A Politico report has linked Clinton's most ardent supporters to the circulation during the 2008 campaign cycle of an e-mail suggesting that Obama was born in Kenya. But no evidence has ever been found connecting this claim to Clinton or her campaign. Since 2008, no fact checker or journalist has uncovered any evidence linking Clinton or her campaign to the start of the birther movement. An ABC News analysis found Trump tweeted 67 times about the birther movement, including after Obama released his birth certificate.
Fact-check No. 7: Trump on the Iraq War
Trump: "I did not support the war in Iraq ... I was against the war in Iraq."
Explanation: Trump expressed support for the invasion of Iraq before expressing some reservations.
Asked by Howard Stern on Sept. 11, 2002, if he was "for invading Iraq," Trump at the time answered, "Yeah, I guess so."
But by Jan. 28, 2003, Trump expressed some concern about the possibility of an invasion, telling Fox Business' Neil Cavuto that President George W. Bush "has either got to do something or not do something, perhaps, because perhaps shouldn't be doing it yet, and perhaps we should be waiting for the United Nations, you know." On March 21, 2003, soon after the invasion of Iraq began, Trump told Cavuto that the war "looks like a tremendous success from a military standpoint." While Trump now portrays himself as having been an outspoken opponent of the invasion, his public statements in the lead-up to the invasion tell a different story.
Fact-check No. 8: Clinton says Trump advocated for the actions the US took in Libya
Clinton: "He actually advocated for the actions we took in Libya. And urged that Gaddafi be taken out, after actually doing some business with him one time."
Grade: Mostly true
Explanation: In a video posted on his YouTube video blog in February 2011, Trump called for intervention in Libya. "It's a carnage," he said. "Now, we should go in, we should stop this guy, which would be very easy and very quick, we could do it surgically, and save these lives." Later he claimed to have never discussed Libya (false) and to have supported a surgical intervention — killing Gaddafi only and not taking any other actions.
Fact-check No. 9: Trump said it was "wrong" that he had been "praiseworthy" of Russian President Vladimir Putin, as Clinton claimed
Clinton: "There's no doubt now that Russia has used cyberattacks against all kinds of organizations in our country, and I am deeply concerned about this. I know Donald is very praiseworthy of Vladimir Putin."
Explanation: Trump has publicly said favorable things about Putin numerous times, usually while criticizing Obama. In a GOP primary debate hosted by NBC News, Trump described his strategy for dealing with Putin, saying, "I would talk to him. I would get along with him." In a recent NBC forum, in which the network separately interviewed Clinton, Trump defended his comments, pointing to strong domestic polling for Putin. When Putin authored an op-ed on Syria in The New York Times, in September 2013, Trump tweeted that it was a "masterpiece for Russia and a disaster for the U.S." Interviewed by MSNBC, Trump said of Putin, "He's running his country, and at least he's a leader, you know, unlike what we have in this country."
Fact-check No. 10: Trump on crime rates
Clinton: "Under the current [New York City] mayor, crime has continued to drop, including murders."
Trump: "You're wrong ... Murders are up."
Grade: Mostly false
Explanation: New York City mayor Bill de Blasio was sworn into office on Jan. 1, 2014. Each of his first two years in office saw an overall drop in the seven major felonies, and so far this year major crimes are down nearly 3 percent, compared with the same period last year. Murder statistics present a slightly more complicated picture during de Blasio's tenure. His first year in office saw 333 murders, two fewer than the year before. But his second year in office saw an uptick to 352 murders. So far this year, murders in New York City are down more than 4 percent from the same period last year (246 murders through Sept. 18, 2016, versus 257 murders in the same span in 2015).
Fact-check No. 11: Clinton: Trump said "he didn't care" if Japan, South Korea and Saudi Arabia get nuclear weapons
Clinton: "And the worst part ... of what we've heard Donald say has been about nuclear weapons. He has said repeatedly that he didn't care if other nations got nuclear weapons — Japan, South Korea, even Saudi Arabia. It has been the policy of the United States — Democrats and Republicans — to do everything we could to reduce the proliferation of nuclear weapons. He even said, well, if there were a nuclear war in East Asia, well, you know, that's fine."
Grade: Yes and no
Explanation: Trump has said that America's allies should pay more of their defense costs. Earlier this year he seemed to say that Japan might be better off if it had nuclear weapons to defend itself from North Korea. At a town hall in March he seemed to support Saudi Arabia's having nuclear weapons but quickly reversed himself. In June he denied that he wanted Japan to get nuclear weapons. He wants America's allies to take more responsibility for their defense and has at times indicated it would be OK for Japan to have access to nuclear weapons to defend itself from North Korea.
Fact-check No. 12: Trump denies saying that pregnancy is an inconvenience to employers
Clinton: "One thing, Lester, he tried to switch from looks to stamina. But this is a man who has called women pigs, slobs and dogs. And someone who has said pregnancy is an inconvenience to employers."
Trump: "I never said that."
Explanation: Trump said just that in an October 2004 interview with NBC's "Dateline." In the interview he said pregnancy is "a wonderful thing for the woman. It's a wonderful thing for the husband. It's certainly an inconvenience for a business. And whether people want to say that or not, the fact is it is an inconvenience for a person that is running a business."
Fact-check No. 13: Trump on stop and frisk
Holt: "Stop and frisk was ruled unconstitutional in New York, because it largely singled out black and Hispanic young men —"
Trump: "No, you're wrong. It went before a judge who was a very against police judge. It was taken away from her, and our mayor, our new mayor, refused to go forward with the case. They would have won an appeal. If you look at it, throughout the country, there are many places."
Grade: Mostly false
Explanation: Holt was correct. In August 2013 a federal district judge ruled the NYPD's stop-and-frisk tactics violated the constitutional rights of minorities, calling it a "policy of indirect racial profiling." Mayor Michael Bloomberg appealed the case. The 2nd Circuit Court temporarily blocked the judge's orders and removed her from the case, finding she had compromised "the appearance of impartiality surrounding this litigation." But the court stopped short of overturning her ruling.
The stop-and-frisk program was still in the midst of the appeals process when newly elected Mayor Bill de Blasio, who supported the district court ruling, settled the litigation and ended the controversial program.
Fact-check No. 14: Trump says stop and frisk works "well"
Trump: "Over 4 — almost 4,000 people in Chicago have been killed. We have to bring back law and order. Now, whether or not in a place like Chicago you do stop and frisk, which worked very well — [former New York] Mayor Giuliani is here, it worked very well in New York. It brought the crime rate way down, but you take the gun away from criminals that shouldn't be having it."
Grade: Yes and no
Explanation: There has been much debate about whether stop and frisk is effective. Trump often cites the example of the tactic being used by police in New York City, as he did this evening. While violent crime fell in New York City while stop and frisk was implemented, the crime rate also fell nationally and in places where police did not employ the tactic. Stop and frisk may have some limited impact, but it is not clear how effective it is. According to NYCLU data, guns were recovered in only 0.2 percent of cases.
According to an NYPD spokesman, the use of stop and frisk has decreased nearly 97 percent in New York City since 2011, and crime has decreased significantly during the same period. NYPD statistics bear this out.
Fact-check No. 15: Clinton claims Trump's tax plan would add $5 trillion to the debt and cost the economy jobs
Clinton: "Independent experts have looked at what I've proposed and looked at what Donald's proposed, and basically, they've said this: that if his tax plan — which would blow up the debt by over $5 trillion and would in some instances disadvantage middle class families, compared to the wealthy — were to go into effect, we would lose 3.5 million jobs and maybe have another recession."
Explanation: Under Trump's current tax and spending proposal, the debt over the next decade would increase by about $5 trillion, according to Moody's latest estimate. An estimate from the Committee for a Responsible Budget says, "Both Clinton and Trump would increase the debt relative to current law — though Trump would increase it by an order of magnitude more, and Clinton's plan would slightly reduce deficits if we incorporated unspecified revenue from business tax reform. Specifically, we estimate Clinton's plans would add $200 billion to the debt over the next decade, while Trump's plans would add $5.3 trillion.
Fact-check No. 16: Trump on the Democratic National Committee hack
Trump: "I don't know if anyone knows it was Russia that broke into the DNC. She's saying Russia, Russia, Russia, but I don't — maybe it was. I mean, it could be Russia, but it could also be China. Could also be lots of other people. It also could be somebody sitting on their bed that weighs 400 pounds, OK? You don't know who broke into DNC."
Grade: Mostly false
Explanation: U.S. officials — speaking on the condition of anonymity because of the sensitive nature of the information — have uniformly told ABC News and other major news outlets that evidence in the Democratic National Committee hack points directly to Russia. In addition, the firm hired by the DNC to respond to the suspected breach, CrowdStrike, conducted an investigation and later issued a statement saying it "identified two sophisticated adversaries" as being behind the hack. "Both adversaries engage in extensive political and economic espionage for the benefit of the government of the Russian Federation and are believed to be closely linked to the Russian government's powerful and highly capable intelligence services," CrowdStrike said. Just last week, the top Democrats on the House and Senate Intelligence committees, Sen. Dianne Feinstein, D-Calif., and Rep. Adam Schiff, D-Calif., issued a statement saying, "Based on briefings we have received, we have concluded that Russian intelligence agencies are making a serious and concerted effort to influence the U.S. election. At the least, this effort is intended to sow doubt about the security of our election and may well be intended to influence the outcomes of the election — we can see no other rationale for the behavior of the Russians."
Fact-check No. 17: Trump says Ford is moving jobs out of the US
Trump: "Ford is leaving. You see that. Their small car division, leaving. Thousands of jobs leaving Michigan, leaving Ohio, they're all leaving."
Grade: Mostly false
Explanation: Though Ford has announced it is moving production of the small Ford Focus to a new plant in Mexico, the company tells ABC the move will have "absolutely no impact on U.S. jobs." While the new plant begins production of the Focus, workers at the Michigan plant that manufactured the car will make two new vehicles.
ABC News' Margaret Chadbourn, Sarah Kolinovsky, Justin Fishel, Luis Martinez, Lauren Pearle, Ali Rogin, Katherine Faulders, Alana Abramson, Ryan Struyk, Ely Brown, Chris Good, Mike Levine, Jordyn Phelps, Jack Date, Erin Dooley and Zunaira Zaki contributed to this report.