The world was watching as Donald Trump and Hillary Clinton clashed face-to-face for the first time.
The Democrat and Republican rivals squared off in a 90-minute debate at Hofstra University in New York - their first head-to-head debate in the race to the White House. It was screened to tens of millions of television viewers in America and live-streamed across the world.
Here are the key points from the passionate debate, as the candidates hurled accusations at each other.
After months of mud-slinging over the airwaves and online it was the first time Trump and Clinton shared a stage.
The pair arrived in the auditorium at Hofstra University in New York to cheers and smiled as they shook hands, Clinton greeting the tycoon with: "Hey, how are you Donald?"
Jobs and the economy
The candidates kicked off with different approaches to the first question on Americans' wealth and work, Clinton looking to future policies while Trump targeted the Democrats' record in government. Clinton noted that it was her granddaughter Charlotte's second birthday as she pledged to achieve gender parity in the workplace and increase taxes for the wealthy.
Trump said the US had lost jobs to Mexico and industry to China and promised to revive the US economy by lowering taxes, cutting regulation and renegotiating trade deals. He repeatedly attacked his rival's husband, former US president Bill Clinton, for the North American Free Trade Agreement that was approved under his administration in the 1990s.
Clinton used the subject of family income to launch a personal attack on Trump, contrasting his charmed start in life with her own.
Emails and tax returns
These were two subjects both candidates could expect to be attacked on. Clinton admitted that she had made a mistake by using a private email system during her tenure as US secretary of state.
Trump said he would only disclose his tax affairs if his rival releases the "33,000 emails" deleted from her private server.
However, Clinton accused Trump of hiding "something terrible", suggesting he may not be as wealthy as he claims, pays a low rate of tax or gives smaller charitable donations than he has claimed.
Trump denied saying climate change was false despite tweeting in January 2014: "Snowing in Texas and Louisiana, record setting freezing temperatures throughout the country and beyond. Global warming is an expensive hoax!"
He also claimed in 2012 that the concept of global warming was "created by and for the Chinese in order to make US manufacturing non-competitive".
The candidates were asked how they would heal race relations in the wake of police shootings that have provoked outrage across the US. Clinton said gun violence is the leading cause of death among young African-American men and tackling the "plague of gun violence" is critical.
The pair clashed on "stop and frisk" laws, with Trump claiming a judge's ruling that the practice was unconstitutional was wrong. He said: "Right now our police are afraid of doing anything" and that if you walk down the streets in places like Chicago, "you get shot". A theme throughout his campaign has been to "make America safe again".
Trump recently dropped a conspiracy theory that Barack Obama was not born in the United States and was therefore ineligible to serve as president. The retreat came after years of campaigning for Obama to release his birth certificate.
In the debate Trump blamed Clinton for starting the false claim that Obama was born in Kenya and said that he was instrumental in achieving the certificate's release. Clinton accused her rival of spreading a "racist lie" that our "first black president" was not an American citizen.
On a rare point of agreement between the candidates, Trump said he supported Clinton's view that people on watch lists or no-fly lists should have restrictions on their ability to buy guns.
"We have to look very strongly at no-fly lists and watch lists," the tycoon said.
Defence and cyber security
After batting off questions over his temperament Trump said he would not use the US's nuclear arsenal unless the US was struck with warheads first. However, he also said he "can't take anything off the table" and referred to issues with Iran and North Korea.
The candidates were quizzed on their views on cyber security, with a focus on Russia. Clinton said the US "is not going to sit idly by" and let hostile nations attempt to hack public or private information. Trump's past praise of Russian President Vladimir Putin left him open to attack. He simply replied "wrong" when the comments were raised.
Trump was quick to bring national security into the debate even when the question was on a separate issue. He first accused Clinton of leaking tactics to Islamic State on her campaign website and criticised the Obama administration for the ascendancy of the terror group. The Democratic candidate said she is hopeful that IS will be eradicated by the end of the year - with taking out its leaders her top priority in office.
In the wake of several deadly terror-related incidents in the US, Clinton said her rival had "consistently insulted Muslims abroad, Muslims at home", while people from within the Muslim community would be key to fighting terror.
Fitness to serve
Both candidates appeared fit and well during the debate. However, sniffling by Trump set chins wagging on Twitter. After Clinton revealed earlier this month that she had been diagnosed with pneumonia, Trump questioned whether she had the stamina to be president. "You have so many different things you have to be able to do and I don't believe Hillary has the stamina," he said.
Clinton said Trump should not talk about stamina until he has tried out the busy schedule she kept up as secretary of state.
Former president Bill Clinton and Melania Trump were among those in the audience at the event, which was expected to be the most watched debate in TV history.
Some 2,000 protesters gathered outside the debate hall, including Hardhats for Hillary, socialists and activists calling for a living wage, police said. Twenty-four people were arrested on mostly disorderly conduct charges.
Trump and Clinton will take part in two more debates before the November 8 election. Their running mates, Tim Kaine and Mike Pence, will square off next week.