When President Donald Trump said this week that there were "very fine people" at the white power rally, he cast "blame on both sides" including the "alt-left" antifa.
First bursting into the headlines when they shut down far-right provocateur Milo Yiannopoulos in February at the University of California, Berkeley, anti-fascists again captivated the public imagination by battling the fascists assembled at the "Unite the Right" white power rally in Charlottesville, Va.
But what is antifa? Militant anti-fascist or "antifa" is a radical pan-leftist politics of social revolution applied to fighting the far right. Its adherents are predominantly communists, socialists and anarchists who reject turning to the police or the state to halt the advance of white supremacy. Instead, they advocate popular opposition, including what happened last weekend in Charlottesville.
There are antifa groups around the world, but antifa is not itself an interconnected organization, any more than an ideology like socialism or a tactic like the picket line is a specific group. Antifa are autonomous anti-racist groups that monitor and track the activities of local neo-Nazis.
The vast majority of anti-fascist organizing is nonviolent. But their willingness to physically defend themselves and others from white supremacist violence and pre-emptively shut down fascist organizing efforts before they turn deadly distinguishes them from liberal anti-racists.
Though antifa are often treated as a new force in American politics, the anti-fascist tradition stretches back a century. The first anti-fascists fought Benito Mussolini's Blackshirts in Italy, exchanged fire with Adolf Hitler's Brownshirts and defended Madrid from Francisco Franco's insurgent nationalist army.
Modern antifa politics can be traced to resistance to waves of xenophobia and the emergence of white power skinhead culture in Britain in the 1970s and 1980s.