A black bloc is a tactic for protests and marches, whereby individuals wear black clothing, scarfs, ski masks, motorcycle helmets with padding or other face-concealing items and often carry some sort of shields and truncheons. The clothing is used to avoid being identified, and to, theoretically, appear as one large mass, promoting solidarity or creating the illusion of a larger group.
The tactic was developed in the 1980s by autonomists protesting squatter evictions, nuclear power, restrictions on abortion, among other things. Black blocs gained broader media attention outside Europe during the 1999 anti-WTO demonstrations, when a black bloc damaged property of GAP, Starbucks, Old Navy, and other retail locations in downtown Seattle.
"The Black Bloc" is sometimes incorrectly reported as being the name of a specific anarchist group. It is, rather, a tactic that may be adopted by groups of various motivations and methods.