Trump and the right's post-Charlottesville bogeyman is 'Antifa,' a movement with a complicated history

After violence and chaos descended on Charlottesville, Virginia, earlier this month during a rally for white supremacists and neo-Nazis, another lesser-known group in attendance suddenly shot into the mainstream political vernacular: "antifa."

President Donald Trump used the word himself at a rally in Phoenix, Arizona, Tuesday evening.

"They show up in the helmets and the black masks and they've got clubs, they've got everything," he said. "Antifa!"

Trump appeared to refer to antifa activists when blamed "many sides" for the Charlottesville violence in his initial statement on the matter. At a press conference later that week, Trump criticized what he called the "alt-left" for "charging with clubs" at the rally.

Antifa activists were among the many counterprotesters that mobilized in response to the "United the Right" white nationalist rally in Virginia. But the network of activists has been making waves across the country long before violence erupted in Charlottesville.

In and around Portland, Oregon, antifa activists smashed windows and hurled smoke bombs during a series of riots following Trump's election. They also took to the campus of the University of California, Berkeley, in February to rail against a scheduled speech from conservative provocateur Milo Yiannopoulos.

The activists, dressed in black and wearing bandanas to obscure their faces, smashed store windows, set fires, threw Molotov cocktails, and rioted during what was originally intended to a be a peaceful protest.

Here's what you need to know about the controversial activist movement: