People who tuned in to the news on the day of Donald Trump’s inauguration were almost as likely to see footage of a limo on fire and a Starbucks window getting smashed as the inaugural ceremony itself. Later in the day, videos of white supremacist Richard Spencer getting punched in the face went mega-viral. All of these images were brought to your attention courtesy of the black bloc, an antifascist protest method that many witnessed for the first time on January 20, but has actually been around since the late 1970s.

What is the Black Bloc?

In her dispatch from the anti-fascist anti-capitalist black bloc that protested Trump’s inauguration, writer Nasha Lennard aptly described the black bloc as “not a group but an anarchist tactic—marching as a confrontational united force, uniformed in black and anonymized for security. Once deployed, the tactic has an alchemic quality, turning into a temporary object—the black bloc.”

Indeed, the black bloc is not a political group or set of views, but a protest method used by some anarchists. The uniform Lennard mentions is a key part of making the bloc work as well as it often does. As the name implies, the people who form a black bloc dress entirely in black from head to toe. Much of the time, black bloc actors will cover their faces using black bandanas or face masks, and/or sunglasses.

An all-black uniform keeps everyone in the group anonymous. As the world saw on inauguration day, people within the black bloc will sometimes emerge from the tight bloc formation to destroy private and corporate property—an act of protest that is entirely illegal—but when everyone looks the same, it’s harder to tell who stayed in the streets and who whipped out a hammer and started smashing windows. There’s safety in the anonymity of the black bloc, and certainly an internal sense of pride and power that comes with amassing in uniform.

Some black bloc members will show up with hammers, bricks, rocks, and other such items that are relatively easy to conceal yet are capable of doing hefty damage. Lighters and flares are also usually on hand for setting things on fire and drawing attention to the group. Depending on the specific protest, the disruption and distraction that black blocs cause can be just as important to the mission of the action as the damage the group leaves in its wake.

Where Did the Black Bloc Come From?

“The term ‘black bloc’ originally described German street protesters in the early 1980s who were associated with the autonomist, anti-nuclear, and squatting movements,” Adam Quinn, a historian of anarchy, tells Complex. “These protesters faced mass arrest, evictions from protest camps, and police violence. As a defensive measure, they wore matching black clothing to mask their identities, as well as helmets and leather jackets to protect them from physical harm. This allowed protesters to engage in actions that would have otherwise involved great risk.”

According to Quinn, it was the high visibility of the tactic that helped it catch on globally in the 1980s: “The black bloc became particularly associated with the anti-globalization protests of the late 1990s and early 2000s, and became revitalized around 2011-2013 through protests against inequality, corruption, and police violence around the globe.”

The Black Bloc in the U.S.

Quinn says that the first recorded use of the black bloc in the United States was in 1988, when protesters amassed at the Pentagon to speak out against U.S.-supported death squads in El Salvador. Protesters aimed to disrupt Pentagon activity by blockading entrances to the building. “It was in protests like that,” Quinn says, “which went beyond picketing and attempted to really disrupt a location or shut down a summit, where the black bloc found its home into the 1990s.”

Quinn notes that the 1999 World Trade Organization protest in Seattle (known as the Battle in Seattle) was a particularly important moment for the black bloc in the States. Tens of thousands of protesters from across the U.S. and the world showed up in Seattle to disrupt the WTO talks, and were very effective. The bloc created a human chain around the Seattle Convention Center where the WTO talks were being held, preventing world leaders from entering the building and effectively shutting down downtown Seattle. Police deployed water cannons, rubber bullets, and tear gas, and arrested 600 people. However, the talks were shut down and Seattle’s chief of police resigned following the protest.

Problems With the Police

Much of what a black bloc does is against the law. Blocs don’t obtain permits for their demonstrations, and of course other tactics such as property destruction are illegal. Beyond the fact of illegality, the anarchist philosophy behind black blocs puts them in direct opposition to the police, and the police in opposition to the bloc. The two entities aren’t designed to get along.

All of this is to say that black bloc participants get arrested—a lot. At the J20 protests alone, more than 200 people were arrested for being a part of or even just covering the black bloc as a member of the press.

Police have also been known to infiltrate and sabotage black blocs. Following protests of the 2001 G-8 Summit in Genoa, police admitted to planting Molotov cocktails in student dorms that were housing anarchist activists in order to justify a raid on the school and brutality against activists.

Doing it Wrong?

Anarchists will occasionally deploy a black bloc when it’s best that they don’t. Because bloc tactics are often unlawful, people involved—or even bystanders—have a decent chance of getting arrested. The key component is that those who willingly participate in the bloc are aware of this risk, and taking it of their own volition. Major issues of safety for others can arise when a black bloc shows up to other groups’ protests and destroys property, etc. at the risk of others present who want to rally or march peacefully.

A recent example of a black bloc putting other people at risk was Ferguson, Missouri, in 2014, when local citizens and people from around the country took to the streets for weeks of protests after the police killing of Michael BrownAnarchists arrived to Ferguson and destroyed property and became aggressive with the police, effectively putting other protesters—who were mostly black and therefore already vulnerable to arrest and police violence—at higher risk.

The black bloc is controversial for many valid reasons: Some activists aren’t interested in property destruction, risking arrest, or engaging violently with the police. Some say that there’s no room in any social justice movement for anything other than permitted marches and rallies. But there’s no denying that the black bloc has had some success (the Battle in Seattle being just one example), and if the J20 protests were any indication, it seems it’s here to stay.