Democratic nominee Hillary Clinton has called out rival Donald Trump over his affinity with online fringe groups — or, as she puts it, people from "the far dark reaches of the internet." In a speech that was first previewed earlier this week, Clinton addressed Trump’s ties to the alt-right, a reactionary group that has propagated online over the past few years. It’s one of the most high-profile offline mentions of the movement so far, and a sign that it’s becoming increasingly central to the presidential campaign.

Clinton has gone after Trump’s online behavior before, particularly his vitriolic Twitter presence, calling him "a man you can bait with a tweet" at the Democratic National Convention. But this time, she specifically tied Trump to the kind of online racism that journalists and groups like the Southern Poverty Law Center have been keeping tabs on for months. "A man with a long history of racial discrimination, who traffics in dark conspiracy theories drawn from the pages of of supermarket tabloids and the far dark reaches of the internet, should never run our government or command our military," Clinton said, accusing Trump of building his campaign "on prejudice and paranoia."

More recently, the Trump campaign hired the CEO of far-right publication Breitbart News, which Clinton accused of propagating "an emerging racist ideology known as the ‘alt-right.’" This "de facto merger between Breitbart and the Trump Campaign represents a landmark achievement for the alt-right," she said. "A fringe element has effectively taken over the Republican Party."

Alt-right or alternative right is a loose term, although there are several explanations online. It’s tied both to specific figures and to a general white supremacy-fueled protest against racial or religious diversity, as filtered through 4chan memes. Clinton drew her definition from The Wall Street Journal, calling it "a loosely organized movement, mostly online, that ‘rejects mainstream conservatism, promotes nationalism and views immigration and multiculturalism as threats to white identity.’"

In this speech, Clinton referred both to Breitbart and to Trump’s casual interactions with online racists. "This is someone who retweets white supremacists online, like the user who goes by the name ‘white-genocide-TM.’ Trump took this fringe bigot with a few dozen followers and spread his message to 11 million people," she said. "His campaign famously posted an anti-Semitic image — a Star of David imposed over a sea of dollar bills — that first appeared on a white supremacist website."

Trump retweeted two separate messages from WhiteGenocideTM early this year, and while he has repeatedly denied that the image represented a Star of David, it was spotted on a white supremacist-leaning message board a week before Trump posted it. In another incident, which Clinton didn’t mention, he retweeted an infographic of fabricated crime statistics previously posted by a neo-Nazi account.

There are no shortage of more traditional white supremacists who support Trump, like former KKK Grand Wizard David Duke — who Clinton also mentioned. But the speech pulled a surprising amount of internet controversy into the real world, especially because before Trump’s rise, Breitbart was best known for an over-the-top fight against "political correctness" that gained steam during the 2014 Gamergate campaign. Clinton worked some of its trollish, attention-grabbing headlines into her speech and Twitter feed, including a reference to the "feminism is cancer" catchphrase popularized by Breitbart editor and one-time Gamergate celebrity Milo Yiannopoulos.

Trump responded after the speech, calling it "very short and lies" in a pair of tweets. "Hillary Clinton's short speech is pandering to the worst instincts in our society. She should be ashamed of herself!" he wrote. His campaign manager said beforehand that Trump’s platform was "not at all" aimed at the alt-right movement, and that she was "not that familiar with it, to be frank with you." Granted, Trump himself has previously claimed to "know nothing about David Duke" as well, despite deploring his bigotry in interviews a decade ago. So parsing any of his campaign’s statements about racism, online or offline, may be a futile effort.