In the biggest speech of her quarter century in politics, Clinton on Thursday accepted the Democratic presidential nomination for the Nov. 8 election with a promise to make the United States a country that worked for everyone.
"We are clear-eyed about what our country is up against. But we are not afraid," she said.
She presented a sharply more upbeat view of the country than her rival Trump offered when Republicans nominated him last week, and even turned one of Republican hero Ronald Reagan's signature phrases against the New York real-estate developer.
"He's taken the Republican Party a long way, from 'Morning in America' to 'Midnight in America,'" Clinton said. "He wants to divide us - from the rest of the world, and from each other."
Clinton portrayed Trump as a threat to the country, saying "a man you can bait with a tweet is not a man we can trust with nuclear weapons."
Vying to be the first woman elected U.S. president, Clinton called her nomination "a milestone."
"When any barrier falls in America, for anyone, it clears the way for everyone. That’s why when there are no ceilings, the sky's the limit," the 68-year-old Clinton said.
On Friday, she will hit the campaign trail with her running mate, U.S. Senator Tim Kaine of Virginia. The two will hold a rally in Philadelphia before setting off on a bus tour of Pennsylvania and Ohio, two Rust Belt states that could be pivotal in the November election.
Trump will campaign in Colorado on Friday and is scheduled to visit Ohio next week.
While her speech was not as electrifying as those given by President Barack Obama and some other prominent Democrats at the Philadelphia convention, Clinton was authoritative and self-assured in her pitch to the American public.
She acknowledged some people still do not know her well.
"I get it that some people just don't know what to make of me. So let me tell you. The family I'm from, well no one had their name on big buildings," Clinton said in a reference to Trump, whose name is plastered across his properties.
She said her family built a better life and a better future for their children, using whatever tools they had and "whatever God gave them."
The speech capped a four-day nominating convention that opened in discord after a leak of hacked Democratic National Committee emails showed party officials favored Clinton over primary rival Bernie Sanders, a U.S. senator from Vermont.
Even though DNC Chairwoman Debbie Wasserman Schultz, a Clinton ally, resigned on Sunday, angry Sanders supporters throughout the week disrupted the convention and undermined efforts by Clinton and Sanders to present a united front.
On Thursday, people familiar with the matter said the FBI is investigating a cyber attack against another Democratic Party group, which may be related to the earlier hack against the DNC.
The incident at the Democratic Congressional Campaign Committee and its potential ties to Russian hackers are likely to heighten accusations, so far unproven, that Moscow is trying to meddle in the U.S. election to help Trump.
Sanders supporters on Thursday wore fluorescent green T-shirts that said "Enough is Enough." Their occasional chants of protest were drowned out by Clinton supporters chanting, "Hillary!"