Hillary Clinton dominated a final series of debate exchanges with Donald J. Trump about national security and gender, telling voters they could not trust her opponent with nuclear weapons and warning that he does not respect women.
Here are a few of the highlights.
■ Asked about a remark he made that Mrs. Clinton lacked a presidential “look,” Mr. Trump repeated the claim, adding that “she doesn’t have the stamina.” In response, Mrs. Clinton ticked off some highlights of her tenure as secretary of state, saying Mr. Trump “can talk to me about stamina” when he accomplishes as much. “He tried to change from looks to stamina, but this is a man who has called women pigs, slobs and dogs,” Mrs. Clinton said. Mr. Trump defended himself before adding that he had planned to say “something extremely rough” to Mrs. Clinton and her family, but decided against it.
■ Mrs. Clinton pressed Mr. Trump’s repeated claim, contradicted by public statements he has made in the past, that he had opposed the Iraq war from the beginning. “Donald supported the invasion of Iraq,” she said. “That is absolutely proved over and over again.” “Wrong,” Mr. Trump interjected. “Wrong.”
■ Mr. Trump insisted again that he had opposed the Iraq war, calling any suggestion otherwise “a mainstream media nonsense.” Lester Holt, the moderator, said, “The record shows otherwise.” Mr. Trump went on to appraise his own temperament, calling it “my strongest asset, maybe by far,” before attacking Mrs. Clinton’s. She smiled. “Woo! O.K.,” she said, beginning her response.
■ Mrs. Clinton hit Mr. Trump for his record of praise for President Vladimir V. Putin of Russia, lamenting that Mr. Trump had “publicly invited Putin to hack into” American communications, as Mr. Trump shook his head. Mr. Trump said he did not think “anybody knows” if Russia was behind the recent hacks of Democratic organizations, wondering aloud if it might instead be China or a single hacker who “weighs 400 pounds” and sits at home.
■ After Mrs. Clinton suggested she was worried about Mr. Trump getting his hands on the nuclear codes, Mr. Trump replied, “That line is getting a little bit old.” Mrs. Clinton mocked Mr. Trump’s “secret plan,” as she called it, to fight the Islamic State, saying he had no true strategy. She also sought to reassure American allies that the country would honor its international commitments, saying some of Mr. Trump’s comments during the campaign had startled them.
■ Asked about his propagation of the conspiracy theory raising doubts about Mr. Obama’s birth, Mr. Trump tried to blame Mrs. Clinton, suggesting falsely that she, too, had questioned the president’s birthplace. “She failed to get the birth certificate,” he said. “When I got involved, I didn’t fail.” Mrs. Clinton said Mr. Trump had “really started his political activity based on this racist lie that our first black president was not an American citizen,” calling his efforts “very hurtful.”
■ Pressed on his refusal to release his tax returns, Mr. Trump repeated an oft-used line that he is facing “a routine audit” that precluded him from releasing the information. Mr. Holt noted that the I.R.S. had said he was free to release anything he wanted. Mr. Trump said he would “release my tax returns, against my lawyers’ wishes,” if Mrs. Clinton agreed to release a cache of her emails.
■ Asked if she believed police officers were “implicitly biased” against African-Americans, Mrs. Clinton suggested that all Americans were susceptible to bias. “I think unfortunately too many of us in this great country jump to conclusions about each other,” she said.
■ Asked about race relations, Mrs. Clinton said that race remained “a significant challenge” in the country, adding that the criminal justice system treated minorities differently. Mr. Trump said Mrs. Clinton “doesn’t want to use a couple of words” — law and order — before defending the contentious stop-and-frisk police strategy. “African-Americans and Hispanics are living in hell,” he said. “You walk down the streets, you get shot.”
■ After Mr. Trump defended his plans to lower taxes on the wealthy, mixing in jabs at Mrs. Clinton, she joked, “I have a feeling that by the end of this evening, I’m going to be blamed for everything that’s ever happened.” Mr. Trump replied, “Why not?” Mr. Holt reminded Mr. Trump that he was speaking during Mrs. Clinton’s allotted time.
■ Mr. Trump boasted about his campaign travels. “You’ve seen me, I’ve been all over the place,” he said. “You decided to stay home and that’s okay.” Mrs. Clinton replied that she did indeed prepare for the debate, adding that she was preparing to be president, too.
■ Hitting Mr. Trump over his tax returns, Mrs. Clinton wondered if there was “something he’s hiding,” before addressing her own use of a private email as secretary of state. “I made a mistake using a private email,” she said. Mr. Trump cut in, “That’s for sure.” Mrs. Clinton added, “I’m not going to make any excuses. It was a mistake.”
■ Mrs. Clinton condemned Mr. Trump for refusing to pay contractors on several projects, saying she was grateful her father had never done business with him. She said the debate crowd included an architect whom Mr. Trump had not paid. “Maybe he didn’t do a good job,” Mr. Trump said.
■ Mrs. Clinton, seeking to portray Mr. Trump as an enemy of working people, said he had “rooted for the housing crisis” because of the financial opportunities it might afford him. “That’s called business, by the way,” he interjected.
■ Mr. Trump — criticizing trade deals approved by Bill Clinton, among others — suggested Mrs. Clinton had failed to improve people’s lives during her decades in public life. As Mrs. Clinton defended her record, he interrupted frequently. “You haven’t done it. You haven’t done it,” he said. “Excuse me.” Mrs. Clinton shot back, “Donald, I know you live in your own reality,” before continuing her answer.
■ Mrs. Clinton, looking toward Mr. Trump, said it was “good to be with” him on the same stage at last. “You have to judge us,” she said, in a response to a question about job creation. “Who can shoulder the immense, awesome responsibilities of the presidency?” Mr. Trump replied that “our jobs are fleeing the country.”
■ Mrs. Clinton criticized Mr. Trump’s fiscal plans as “trumped-up trickle-down economics,” before saying he had received millions of dollars of support from his father. “My father gave me a very small loan,” he replied, before appearing to hesitate while addressing Mrs. Clinton. “Secretary Clinton? Is that O.K.?” he said of her title. “Good.”