At a protest at NYU on Thursday, antifa activists ripped a Donald Trump hat from a man's head and set it on fire. View Full Caption DNAinfo/Noah Hurowitz

NEW YORK CITY — A movement seeking to take down fascists has taken the spotlight since Donald Trump's inauguration — smashing windows, clashing at the University of California in Berkeley and punching Nazi-saluting activist Richard Spencer during a TV interview.

But "antifa," which stands for anti-fascist, has been "dedicated to research on, and act against, fascist cultural and political organizing in New York City" since at least 2010, according to the website for the New York City "antifa" movement.

Members most recently clashed with police and supporters of far-right comedian Gavin McInnes at a protest they organized outside McInnes' speaking event at New York University Thursday night.

The protests turned violent and led to 11 arrests, including one of a McInnes supporter accused of attacking a DNAinfo New York and Gothamist reporter.

At Thursday's NYU protest, several antifa activists attacked a McInnes supporter who was wearing one of Donald Trump's signature "Make America Great Again" hats, ripped the hat from his head and set it on fire.

Antifa members maintain a blog where they advocate for jailed members of their movement and "out" New Yorkers who they say identify as or sympathize with anti-Semites, neo Nazis, white supremacists and nationalists.

In December, they advocated for a boycott of the Brooklyn Commons, a "progressive" venue in downtown Brooklyn, after the owner hosted an anti-Semitic speaker, 9/11 conspiracy theorist Christopher Bollyn.

They also helped get a popular Brooklyn music festival last June to rebook several shows planned for a bar that had previously hosted a white power music event.

The people behind the Antifa NYC website did not immediately respond to an inquiry from DNAinfo.

But members told The Nation last month that their movement "﻿combines radical left-wing and anarchist politics, revulsion at racists, sexists, homophobes, anti-Semites, and Islamophobes, with the international anti-fascist culture of taking the streets and physically confronting the brownshirts of white supremacy, whoever they may be."

According to The Nation, the antifa movement takes many forms, but one of its defining characteristics is a complete refusal to engage with people or institutions that they believe are fascist.

Antifa's roots are in 20th-century European militant squads who fought against Nazis in Germany as early as the 1920s, as well as other self-described fascist or nationalist movements or parties in Spain, Austria and England, according to The Nation.

In the United States, they have gone after the Ku Klux Klan and "white power" musicians, according to The Nation, and are not opposed to the use of violence or physical confrontation.