Over the weekend, violence exploded in Charlottesville, Va., between a group that included white supremacists and neo-Nazis, and another made up of counter-protestors.
The violence was punctuated by the death of Heather Heyer, 32, who was killed when a white supremacist rammed his car into a group of counter-protestors.
READ MORE: Charlottesville: Woman dead after violence at far-right rally, 2 cops killed in helicopter crash
If you were following Twitter over the last few days, one word kept coming up among many who supported the right-wing protestors: Antifa.
What is Antifa?
Antifa is simply the short-form for anti-fascist.
Who are Antifa?
There is not simply one ‘Antifa’ organization in the U.S.; there is the TORCH Antifa Network.
“‘Antifa,’ are a subset of the anarchist movement and focus on issues involving racism, sexism, and anti-Semitism, as well as other perceived injustices,” the U.S. Department of Homeland Security says.
According to the BBC, they oppose many anti-immigration policies U.S. President Donald Trump has sought to enact, such as the travel ban.
While the list of policies Antifa operatives are opposed to is long, their primary focus is on fighting far-right ideology.
History of Antifa
Some suggest the Antifa’s history stretches back to England in the late 1800s, but they can clearly be traced to the 1920s and 1930s, when militant leftists battled fascists in Nazi Germany and Mussolini’s Italy, CNN reports.
Why do many Antifa activists wear black clothing?
Many activists will wear bandanas and masks in order to hide their identities from the authorities.
WATCH: Protesters don masks during demonstrations against Milo Yiannopoulos
Many Antifa activists dress in black from head-to-toe and are known as the Black Bloc.
The decision to don black garb is with the intention of giving the appearance of solidarity, Policemag.org reports.
Is Antifa violent?
Violence and property damage have broken out at Antifa gatherings in recent months.
When Milo Yiannopoulos was scheduled to speak at UC Berkeley in April, he was met with crowds of protestors, including members of the Antifa.
READ MORE: UC Berkeley in lockdown amid protest against Milo Yiannopoulos
There are varying reports on how many Antifa agitators were there, but Homeland Security notes there were 100 there. Wired Magazine pegged the number at 150, saying protestors broke windows and shot fireworks at police until the event was cancelled.
CNN reported that masked protestors dressed in black clothing tossed Molotov cocktails and smashed windows at the student union center where the conservative writer was scheduled to speak.
And in June 2016, some demonstrators punched and threw eggs at people as they left a Trump rally in San Jose, Calif., the Atlantic reports.